The costs of appeal are assessed against the defendant.

1. A declaration of intention may be cancelled if there is an error in the material part of the contents of a juristic act;

A major mistake in a juristic act shall be such important to the extent that the voter would not have made such a declaration if he had not made such a mistake, and it shall be so important that he would not have made such declaration of intention if he had made such a declaration of intention in his place of general delivery.

(1) In a case where a mistake exists in the important part of a juristic act, and where it is apparent that the purpose of the contract would not have been achieved if it was known prior to the conclusion of the contract due to a mistake in the current status and boundary of the land of age, and that it would not have been concluded before the conclusion of the contract, the mistake in the important part of the contract is recognized (see, e.g., Supreme Court Decisions 67Da2160, Mar. 26, 196; 74Da54, Apr. 23, 1974). In a case where a mistake occurs in the important part of the contents of the juristic act, such declaration of intention may be revoked, but where such mistake is caused by a gross negligence of the sworn, it shall not be revoked.

Here, the term “serious negligence” refers to a gross negligence of care normally required in light of the name, type, purpose, etc. of the voter’s act.

(See Supreme Court Decisions 92Da25830, 25847, Nov. 24, 1992; 2002Da708844, Apr. 11, 2003, etc.). Barring special circumstances, it cannot be deemed that there is a duty of care to confirm in advance whether the subject matter of sale is accurately consistent with that on the cadastral map by means of surveying the purchaser or comparing with the cadastral map, etc.

2. On November 12, 1985, the lower court recognized that the instant sales contract was lawfully revoked by the Plaintiff’s declaration of revocation on the ground of mistake and sought the return of the down payment.