1. The plaintiff's appeal is dismissed.

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

The purport of the claim and appeal is the purport of the appeal.

1. The reasoning for the court’s explanation of the instant case is as stated in the reasoning of the judgment of the court of first instance, except for adding the judgment under paragraph (2) below to the Plaintiff’s new argument at the court of first instance, and thus, this is acceptable in accordance with the main sentence of Article 420 of the Civil Procedure Act.

2. Determination on the Plaintiff’s assertion of revocation of declaration of intent due to mistake

A. At the time of entering into the instant lease agreement, the Plaintiff clearly stated that the instant building was leased to the Defendant for the purpose of operating the party hall, and the Defendant became aware of the purpose of the Plaintiff’s establishment in the course of discussing the establishment of the party hall, including the Plaintiff and the party hall, etc., and the Plaintiff knew that the instant building was not used for the party hall business due to the Defendant’s failure to obtain permission to change the purpose of use of the instant building or to cooperate in the procedure for changing the purpose of use.

As the grounds of appeal of this case containing such intention stated above arrived at the Defendant, the above contract was revoked pursuant to Article 109(1) of the Civil Act, and thus, the Defendant is obligated to pay to the Plaintiff the lease deposit amount of KRW 30 million and damages for delay.

B. The declaration of intent in the relevant legal doctrine may be cancelled when there is an error in the important part of the content of a juristic act, and in a case where there is an error in the motive for the declaration of intent, it may be cancelled only when the parties have made the motive as the content of the declaration of intent (see, e.g., Supreme Court Decision 87Meu1271, Jan. 17, 1989). The term “an error in the important part of a juristic act” means an important part to the extent that the observer would not have made the said declaration of intent if there was no such an error, and such an expression of intent would not be made if the observer had made the place of the general person who