[2] The meaning of "serious negligence" under the proviso of Article 109 (1) of the Civil Code

[3] The case holding that the cancellation of a sales contract was recognized on the ground of mistake on the ground that there was no gross negligence on the part of the competitor in light of the overall circumstances, such as the mistake of motive constitutes an important part of a juristic act and the mistake caused by

[2] When a mistake is caused by a serious negligence of the voter, it shall not be revoked. The term "serious negligence" here means a lack of attention that is normally required in light of the occupation, type, purpose, etc. of the voter.

[3] After the conclusion of a sales contract for a building, it was known that the building was built by breaking the building line, but the seller's order of removal can be cancelled through administrative litigation because the seller's legal expert's consultation shows that it is difficult for the buyer to cancel the order of removal through administrative litigation. Thus, if the buyer believed the horse and performs his duty of payment without cancelling the sales contract, it would not be the motive mistake regarding the sales contract. However, it is deemed that the buyer and the seller expressed the contents of the sales contract between the buyer and the seller. Furthermore, if the buyer and the general public knew that the part in the building line was removed, the buyer would not purchase the building site and the building. Thus, the buyer's agreement constitutes an error in the important part of the contents. Meanwhile, in light of all circumstances such as the buyer's active action that the buyer would not remove part of the building, it can not be said that the buyer's negligence is attributable to the buyer's gross negligence.

On the third ground for appeal

As to the defendant's assertion that the lawsuit of this case was unlawful because it violated the subordinate agreement between the plaintiff and the defendant, the court below made a statement to the investigation agency on August 28, 1995 that the defendant would not be held liable for any civil or criminal liability in relation to the above sales contract, on condition that the defendant, in relation to the plaintiff's appeal case against the public official in charge of the Nam-gu office's office, etc., the plaintiff made a statement that the building of this case was infringed upon in the course of the sales contract for the site and building of this case. However, unlike the above promise in the investigation process, the defendant made a statement that the plaintiff was aware that the building of this case was constructed in the course of the sale and purchase, unlike the above promise in the course of the investigation, and recognized the fact that the plaintiff collected and discarded the above statement from the defendant and the defendant, according to the above facts, there was a separate agreement between the plaintiff and the defendant to invalidate the above statement. In light of the records, the judgment of the court below is just and there is no error in law such as misapprehension of legal principles as litigation and incomplete.

On the second ground for appeal

In order to cancel a juristic act on the ground that the mistake in the motive constitutes an error in the important part of the contents of the juristic act, it is sufficient to indicate the other party the motive as the content of the juristic act, and it is deemed sufficient to conclude that there is an agreement between the parties to separately consider the motive as the content of the juristic act (see Supreme Court Decisions 88Meu31507, Dec. 26, 1989; 95Da5516, Nov. 21, 1995). However, the mistake in the contents of the juristic act must be an important part to the extent that it would have been deemed that the general public would not have made such a declaration if it had made such a declaration of intent. (See Supreme Court Decisions 87Meu1271, Nov. 17, 1989; 93Da5487, Mar. 26, 1996; 200Da54697, Nov. 26, 1996.

The court below decided on March 1994, where 10 days have passed since the conclusion of the sales contract on the site and building of this case between the plaintiff and the defendant, that the defendant, the seller, was at issue of building construction by 1.45 meters, notified the plaintiff as the purchaser, and decided on whether to cancel the contract. At that time, the defendant knew about the plaintiff's legal office that he well-known to the plaintiff. Since the above building was a building where the inspection of completion was lawfully completed, if the head of the Gu files a lawsuit against the head of the Gu to cancel the order to remove it, the court below did not have any problem, such as introducing the attorney without a mold, and introduced the plaintiff himself to the lawsuit without consultation with the attorney's office. Thus, the plaintiff himself can be seen as not being able to have been aware that part of the above building was not removed, and it was found that part of the building building of this case was completed by the defendant's payment to the defendant without cancelling the above sales contract and the fact that the plaintiff had not been aware that it was an important motive for the plaintiff to remove the building of this case.

In the same purport, the court below's decision that the plaintiff's expression of intent to cancel the contract is legitimate on the ground that the contract of this case was made by mistake is just and there is no error of law such as misunderstanding of legal principles as to mistake.

On the first ground for appeal

As seen above, inasmuch as the instant sales contract was concluded by mistake and its revocation was lawful, the argument that the lower court failed to determine whether the Plaintiff renounced the right to rescind the instant sales contract is unlawful cannot be accepted without examining further to the extent that it is deemed that the lower court’s determination was unlawful (under the records, there was no such assertion up to the lower court’s determination). The argument is without merit.

Therefore, the appeal is dismissed and the costs of appeal are assessed against the losing party. It is so decided as per Disposition by the assent of all participating Justices on the bench.

Justices Lee Don-hee (Presiding Justice)