1. The plaintiff's appeal is dismissed.

2. The costs of appeal shall be borne by the Plaintiff.

Purport of claim and appeal

The first instance court.

1. Basic facts

A. On September 20, 2018, the Plaintiff entered into a sales contract with the Defendant for the 3rd floor D (hereinafter “instant real estate”) owned by the Defendant (hereinafter “instant sales contract”) and paid the Defendant the down payment of KRW 12 million on the same day.

B. The contract of sale and purchase of the above real estate is stipulated as the special terms and conditions, which read as “the sale and purchase contract at the present facilities, and matters not stated in the special terms and conditions, shall conform to the provisions of the Civil Act and the general practices of sale and purchase

C. On October 15 through October 16, 2018, the Defendant received contact from the residents of Eho Lake (hereinafter “instant E”), the lower floor below the instant real estate, and carried out a waterproof construction of the outer wall of the instant real estate around which October 16, 2018.

【Ground for recognition】 Evidence Nos. 1 through 4, 5, and the purport of the whole pleadings

2. The assertion and judgment

A. The Plaintiff’s assertion 1) concluded the instant sales contract on the premise that there is no defect related to water leakage in the instant real estate, and whether there exists any defect related to water leakage in the instant real estate constitutes an important matter in the instant sales contract. However, since water leakage in subparagraph E of the instant real estate occurred and the Defendant waterproof Construction of the outer wall of the instant real estate, there was a defect related to water leakage in the instant real estate. In addition, even though the instant real estate was illegally expanded, the Plaintiff was not notified of the said fact before the conclusion of the sales contract. As such, there was a defect related to water leakage in the instant real estate, and the illegal extension of the real estate constitutes a cause for cancellation of the contract, and the Plaintiff’s cancellation of the instant sales contract and sought the return of the down payment paid to the Defendant by reinstatement. 2) The Defendant did not notify the Plaintiff at the time of the conclusion of the instant sales contract