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

[3] The case holding that it does not constitute an error due to gross negligence that a reconstruction association which entered into a reconstruction apartment design service contract with a building professor who established a building research institute without a qualification as an architect did not investigate the other party's qualification as an architect and did not know his qualification as an architect

[2] When there is an error in the important part of the contents of a juristic act, the declaration of intention may be cancelled, but the error may not be cancelled if the error was caused by gross negligence of the person who made the mark, and "serious negligence" in this context refers to a lack of attention ordinarily required in light of the name, type, purpose, etc. of the mark.

[3] The case holding that the error of the reconstruction association is not due to gross negligence, on the ground that the reconstruction association cannot be deemed to have a duty of care to present an architect qualification certificate or to check and confirm the existence of a qualification for an architect organization, on the ground that it is not a matter of general public, since the reconstruction association has no choice but to believe that it is naturally qualified as an architect, in case where the number of architectural schools in the United States and it was registered as an architect with the trade name of "(title omitted) construction research institute" and it was introduced that it was registered as an architect and that it was included in the construction design business.

Based on adopted evidence, the court below acknowledged the following facts: (a) the plaintiff was not eligible as an architect under the Certified Architects Act; (b) the plaintiff operated the "Construction Research Institute" for the main purpose of construction design research, construction consulting, etc.; (c) on May 17, 200, the plaintiff entered into a design service contract with the promotion committee of the reconstruction association of this case, a telegraph of the defendant for the purpose of reconstruction; (d) on June 18, 2000, the defendant association was formed and the non-party was elected as the head of the association; and (e) on August 21, 200, the defendant confirmed on August 21, 200 that the above construction research institute was not an architect registered with the Certified Architects Association; and (e) concluded the contract of this case with the plaintiff without qualification to cancel the contract of this case for the reason that the plaintiff violated Article 43 of the Certified Architects Act and could seriously affect the reconstruction project; and (e) the defendant presented a copy of the certificate of registration to the plaintiff 21 and the defendant.

2. Determination on the grounds of appeal (the grounds of appeal on supplement after the expiration of the period are within the scope of supplement)

A. The court below held that the contract of this case is a contract which includes the necessary design drawing until the completion of the reconstruction project and the business related to the construction administration necessary for the reconstruction project. In the time of applying for the approval of the reconstruction project or the subsequent modification of the design drawing, if the architect cannot display the design drawing and design drawing, it would be difficult to promote the reconstruction, and under the Certified Architects Act, the architect is granted the qualification for the design prohibited by the architect, and if the design of this case is likely to cause danger to the general public or cause injury to the people, it would be subject to aggravated punishment in light of the fact that the design of the building of the same size as the reconstruction apartment of this case is not only the design ability of the designer, but also the design ability of this case, and it is also an important element of the contract of this case. The plaintiff did not meet such qualification and the defendant union concluded the contract of this case without knowledge, and thus, the contract of this case was concluded by the defendant union.

In order to establish a mistake in the important part of the contents of a juristic act, it is objectively obvious that the indication and the doctor should be objectively determined in light of the purpose pursued by the arbitrator. In light of the importance of the qualification as an architect in the design service of this case, as decided by the court below, if the defendant knew that he was not qualified as an architect, he would have not concluded the design service contract of this case with the general public. Thus, in this case, the mistake of the defendant is deemed to constitute an error in the important part.

The decision of the court below to the same purport is just, and there is no error of law as otherwise alleged in the ground of appeal, such as misconception of facts due to violation of the rules of evidence or incomplete deliberation, misapprehension of legal principles as to

B. (1) The court below rejected the Plaintiff’s assertion that the Defendant was aware of, or could have been sufficiently anticipated at the time of commencing the service business of this case or at the time of concluding the contract of this case, that the Plaintiff was aware of, the fact that the Plaintiff was not an architect, on the ground that there was no evidence to acknowledge it. Since it appears to be a judgment on the Defendant’s mistake that there was gross negligence, the ground of appeal that there was omission of

(2) When there is an error in the important part of the contents of a juristic act, the declaration of intention may be cancelled, but the error may not be cancelled if it was caused by gross negligence of the sworn, and "serious negligence" in this context means a lack of attention that is ordinarily required in light of the name, type, purpose, etc. of the sworn (see Supreme Court Decision 9Da64995 delivered on May 12, 200, etc.).

As recognized by the facts and records of the court below, if the plaintiff introduced that the number of building schools in the United States and the (title omitted) architectural research institute was registered as a person who has entered into the contract of this case with the trade name of "(name omitted) architectural research institute" before and after the conclusion of the contract of this case and was registered as an architect, and that the construction design business was carried out, the plaintiff was bound to believe that the plaintiff is qualified as an architect as a matter of course from the perspective of ordinary people. Thus, the defendant cannot be deemed to have a duty of care to require the presentation of an architect qualification certificate or to inquire about whether the plaintiff is qualified as an architect organization, and it cannot be deemed that the defendant has a duty of care to confirm it without the plaintiff's qualification. Even if the plaintiff prepared the contract of this case and delivered the business registration of "(name omitted) construction research institute" to the defendant without the plaintiff's qualification, such act does not constitute an act to inform the plaintiff's qualification. Thus, it cannot be viewed that the defendant did not know the plaintiff's qualification significantly due to the lack of care due to gross negligence.

Although the reasoning of the court below is insufficient, the court below's rejection of the plaintiff's assertion that the defendant's mistake was due to his gross negligence in light of the above's reasoning is just and there is no error of law such as misconception of facts or misunderstanding of legal principles as to gross negligence due to a violation of the rules of evidence or incomplete trial as alleged in the ground of

3. Therefore, the appeal is dismissed. It is so decided as per Disposition by the assent of all participating Justices on the bench.

Justices Lee Ji-dam (Presiding Justice)