The judgment below is reversed, and the case is remanded to the Incheon District Court.

The grounds of appeal are examined.

1. Any party or any other party may freely escape from the binding force of a contract by waiving the down payment or repaying the amount of the down payment at the stage of which only the down payment is paid; and

However, when the contract is fully implemented due to the payment of intermediate payment, etc., the seller cannot escape from the duty to transfer the ownership of real estate to the buyer unless the contract is revoked or rescinded.

Therefore, when they reach such a stage, the seller is in a fiduciary relationship in which the buyer cooperates in preserving the buyer's property and protects and manages the buyer's pecuniary advantage.

From that time, the seller should be deemed to constitute “a person who administers another’s business” as stated in the crime of breach of trust.

The seller in such position disposes of the real estate to a third party before transferring the ownership of the real estate to the buyer according to the terms of the contract and completing the registration following the disposal to the third party is an act that interferes with the buyer's acquisition or preservation of the real estate.

This is an act of undermining a fiduciary relationship with a buyer, and the crime of breach of trust is established (Supreme Court Decision 2017Do4027 Decided May 17, 2018). Such a legal doctrine cannot be viewed differently in a real estate exchange contract.

In other words, in light of the social norms and the good faith principle, when the exchange contract reaches the stage of full-time implementation, the party to whom the obligation was performed is under a fiduciary relationship in cooperation in preserving the other party's property, and protecting and managing the property interest.

2. Review of the first instance judgment and the reasoning of the lower judgment reveals the following facts.

A. On May 1, 2007, the Defendant exchanged 85 square meters and 705 square meters among the land owned by the Incheon Strengthening-gun C (hereinafter referred to as “land”) and the land owned by the victim and the land owned by the victim.