If an heir has dementia, can't the inherited real estate be sold? Adult guardianship and permission to dispose of residential property

The key point: If an heir lacks the capacity to judge due to dementia or similar, in principle the inherited real estate "cannot be sold right away." The estate-division agreement that is a precondition to selling does not validly form without the capacity to make a declaration of intent (Civil Code art. 3-2), and to take part in the agreement or sell on the person's behalf, an adult guardian chosen by the family court is needed. Further, if the property to sell is the person's residence, even the guardian needs separate permission from the family court (Civil Code art. 859-3). The petition and ruling to begin guardianship are at the family court; petition support goes to a lawyer or judicial scrivener, registration to a judicial scrivener, and valuation and tax to a real-estate appraiser and tax accountant; the sale brokerage is ours—each an independent business, contracted with separately.

You want to sell an inherited property such as the family home, but a parent or sibling who is an heir has dementia—when this happens, "why can't it be sold" and "how should we arrange things" become the first worry. You cannot proceed by leaving the person out, yet the family cannot sign on their behalf either. Moving without knowing the order of procedures risks a hard-won contract being voided later.

This article organises, from the real-estate viewpoint, why a sale stalls when an heir lacks capacity, and the steps up to when it can be sold. Whether guardianship can be begun, and individual legal judgments, are the field of the lawyer, judicial scrivener and family court; this article is general information only.

Yotsuba Real Estate Co., Ltd. (四葉不動産株式会社), based in Bunkyo, Tokyo, provides appraisal of inherited real estate and sale brokerage. Where an heir with dementia is involved, you can consult us from what can be confirmed before selling.

Why does a sale stall when an heir has dementia?

To sell inherited real estate, the usual flow is to settle the estate-division agreement that fixes whose property it is, do the inheritance registration, and then proceed to the sale. But an estate-division agreement is a legal act by all the heirs together, and each heir needs the capacity to make a declaration of intent (the ability to understand and judge matters).

Article 3-2 of the Civil Code provides that "if a party to a legal act did not have mental capacity at the time of the declaration of intent, that legal act is void" (newly established by Act No. 44 of 2017, in force 1 April 2020). An estate-division agreement joined by an heir who lacks the capacity to judge due to dementia has that person's declaration of intent voided, and the whole agreement fails to form.

Stage	When there is an heir who lacks capacity
Estate-division agreement	The person's declaration of intent is void; the family cannot sign or act as agent on their behalf
Inheritance registration	Without the division settled, the title change toward a sale does not progress
Sale contract	If the person is a party, a contract made while lacking capacity is void

So it is not that it "cannot be sold," but that the procedure to appoint someone who can lawfully judge and sign on the person's behalf (an adult guardian) is needed first.

When an adult guardian is appointed, when and how can it be sold?

For a person who lacks capacity, the family court chooses an adult guardian. Article 7 of the Civil Code provides that the family court may, on the petition of the person, their spouse or a relative within the fourth degree etc., make a ruling to begin guardianship for a person who is in a constant state of lacking the capacity to discern right from wrong due to a mental disorder; Article 8 makes a person for whom guardianship has begun an adult ward, to whom an adult guardian is attached.

Once an adult guardian is chosen, they can join the estate-division agreement and become a party to registration and the sale on the person's behalf. The rough order is as follows.

Order	Content	Who handles it
1	Petition to begin guardianship (to the family court)	The person, a relative, etc.; document support from a lawyer or judicial scrivener
2	The family court's ruling and appointment of the adult guardian	Family court
3	The adult guardian joins the estate-division agreement	Adult guardian (in a position to protect the person's interest)
4	Inheritance registration	Judicial scrivener
5	Sale contract and settlement (for a residence, the family court's permission is a precondition)	The seller (guardian) + brokerage is ours

Note that the guardian is in a position to protect "the person's interest." They cannot agree to a division that sells cheaply for the relatives' convenience or reduces the person's share. If the guardian is also one of the co-heirs, their interests conflict, so a special agent must be appointed separately (Civil Code arts. 826 and 860).

The thinking on selling co-owned inherited real estate is also useful in Organising the consent of all heirs when selling co-owned real estate (Japanese).

Why does selling a residence need the family court's permission?

Even with an adult guardian appointed, that alone does not let them freely sell real estate in the person's name. Article 859-3 of the Civil Code provides that for an adult guardian to dispose, on behalf of the adult ward, of a building used for their residence or its site—by sale, lease, termination of a lease, creation of a mortgage, or any other disposition equivalent to these—they must obtain the permission of the family court.

Because losing one's place to live greatly affects the person's life and mental state, from the viewpoint of protecting the person, the disposition of residential real estate specially requires the family court's permission. A sale of residential real estate made without permission is understood to be void (as in the National Tax Agency's written reply, among others).

Character of the property	Family court permission (art. 859-3)
A building and its site the person now lives in, lived in before, or plans to live in	Required (a sale without permission is void)
Inherited real estate that is not the person's residence	Permission under art. 859-3 is not required; but the guardian's duty of care and reporting to the family court remain

"Used for residence" is said to tend to be interpreted relatively broadly in practice, and judging whether it applies is the field of the family court and the guardian. We cannot assert "permission is / is not required." The thinking on sales involving residence-related rights such as a spousal right of residence is also useful in Organising the sale of a building with a spousal right of residence (Japanese).

Is there a way to sell before the estate division?

We also hear "we can't wait until guardianship begins" or "we want to sell before the division," but as long as there is an heir who lacks capacity, you cannot sell first by leaving the person out. The conceivable paths are limited.

Path	Point to note
Sell after waiting for guardianship to begin	The standard flow. If it is the person's residence, the family court permission under art. 859-3 is also needed
Renounce inheritance to leave the group of heirs	A person who lacks capacity cannot do this alone; the guardian's involvement is needed. Not a choice to make lightly
Where there is a will	The person's participation in an agreement may become unnecessary; but the will's validity must be confirmed separately

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In every case, feasibility depends on the individual circumstances and legal judgment. There is information touting a "shortcut to selling before division," but a method that departs from protecting the person risks being voided later. However much you are in a hurry, not skipping the guardianship procedure is often the shortest route in the end. Confirm the need for and feasibility of procedures with a lawyer, judicial scrivener or the family court.

Who do you ask for the guardianship petition, and who handles the sale? (Separate mandates)

A sale involving an heir with dementia spans different businesses: guardianship, registration, tax and real estate. Getting the order wrong can lead to contracting before the guardian is appointed, or to forgetting the residence permission.

Role	Who handles it
Appraisal, brokerage, important-matters explanation, settlement	Real-estate transaction business (our company)
Ruling to begin guardianship, permission to dispose of residential property	Family court
Support for the petition to begin guardianship, judgment on conflicts of interest or disputes	Lawyer / judicial scrivener
Inheritance registration, checking the guardianship registration	Judicial scrivener
Calculating and filing inheritance tax and capital-gains tax	Tax accountant
Appraisal (valuation) of the real estate	Real-estate appraiser

A ruling to begin guardianship and a petition for permission to dispose of residential property are family court procedures listed in appended table 1 of the Domestic Relations Case Procedure Act. Preparing and supporting the petition documents is the work of a lawyer or judicial scrivener; we do not act as agent.

These are each independent businesses, and you contract with them separately. We handle the real-estate side of the sale; support for the guardianship petition and the judgment on conflicts of interest go to a lawyer or judicial scrivener, registration to a judicial scrivener, inheritance and capital-gains tax to a tax accountant, and appraisal valuation to a real-estate appraiser. We do not receive referral fees.

How can you consult Yotsuba Real Estate about selling real estate where an heir has dementia?

Families who have an heir whose capacity to judge has declined, such as through dementia, and who want to sell inherited real estate, can contact Yotsuba Real Estate directly to request appraisal and sale brokerage. Please first tell us:

• The location of the real estate to sell and the current state of the registered title
• The number of heirs and the situation of the person with declined capacity (whether a guardian already exists)
• Whether that property is the residence of the heir who lacks capacity
• Whether there is a will concerning the inheritance

Yotsuba Real Estate organises, from the registration and inheritance situation, the parties and the steps of the sale, and tells you what can be confirmed before selling. Support for the guardianship petition and individual legal judgments go to a lawyer or judicial scrivener, the ruling and the residential-property disposition permission to the family court, registration to a judicial scrivener, and tax to a tax accountant—each independent businesses that you contract with separately.

Consult Yotsuba Real Estate about selling inherited real estate where an heir has dementia—initial consultation is free

In your message, write "sale of real estate where an heir has dementia" and include the location of the property and the heirs' situation. Without presuming whether it can be sold, we begin with organising the order of procedures and who to refer each part to.

Frequently asked questions

Q. My parent has dementia. Can't we just discuss it as a family, sell the home, and sign on their behalf?
A. An estate-division agreement or sale contract joined by an heir who lacks capacity does not form, because the person's declaration of intent is void (Civil Code art. 3-2). The family cannot sign or act as agent on their behalf; the procedure to appoint an adult guardian chosen by the family court is needed first. Confirm feasibility and steps with a lawyer or judicial scrivener.

Q. Once an adult guardian is appointed, can we sell the home right away?
A. The guardian can become a party to the agreement or sale on the person's behalf, but if the property to sell is the person's residence, separate family court permission is needed (Civil Code art. 859-3). A sale of residential property without permission is understood to be void. Judging whether it is a residence is the field of the family court and the guardian.

Q. Can I (the child) become the guardian?
A. A relative may sometimes become guardian, but the family court chooses. If the guardian is one of the co-heirs, their interests conflict in the estate division, so a special agent may need to be appointed separately (Civil Code arts. 826 and 860). Consult a lawyer, judicial scrivener or the family court on the appointment and conflict-of-interest judgment.

Q. Does the guardianship procedure take time? Can we look for a buyer first?
A. A ruling to begin guardianship and permission to dispose of residential property take a certain period. Because a contract made before the guardian is appointed or permission is granted risks being void, keeping the order is safer. We can advise, in parallel with the procedure, on organising market conditions and preparing the sale, and proceed to contract and settlement once the requirements are met.

Sources

The following public materials are starting points for investigation. Laws are amended, so check the current text, enforcement date and latest amendment on e-Gov Law Search. All were consulted on 22 October 2026. They do not establish the feasibility of an individual sale or the need for guardianship. The sources below are in Japanese.

• e-Gov Law Search: Civil Code, art. 3-2 (mental capacity; newly established by Act No. 44 of 2017, in force 1 April 2020), arts. 7 and 8 (ruling to begin guardianship; the adult ward), arts. 826 and 860 (conflict-of-interest acts; special agent), art. 859-3 (permission to dispose of the adult ward's residential real estate)
• e-Gov Law Search: Domestic Relations Case Procedure Act, appended table 1 (cases for a ruling to begin guardianship; cases for permission to dispose of the adult ward's residential real estate)
• Supreme Court, General Secretariat, Family Bureau, "Overview of Adult Guardianship Cases": public material on the use of the adult guardianship system; check the latest edition from the judicial statistics / other statistical information on the Courts website (consulted 22 October 2026)

This article provides general information. Individual legal judgments require review by the appropriately qualified professional. It does not guarantee the need for guardianship, the need for permission to dispose of residential real estate, or the feasibility of a sale.

Joji Uramatsu (浦松 丈二), Representative Director and licensed real estate transaction specialist, Yotsuba Real Estate Co., Ltd. (四葉不動産株式会社). We provide appraisal of inherited real estate and sale brokerage. Author profile

Updated: 22 October 2026