1. Revocation of a judgment of the first instance;

2. The plaintiff's claim is dismissed.

3. All costs of the lawsuit shall be borne by the Plaintiff.

1. Basic facts

A. On August 21, 2010, the Defendant entered into a lease agreement with C, setting the lease term of KRW 52 million, monthly rent of KRW 2.6 million (hereinafter “instant lease agreement”). From August 21, 2010 to August 20, 201, the Defendant entered into a lease agreement (hereinafter “instant lease agreement”).

B. Upon entering into the instant lease agreement, the Defendant and C agreed that the lessee may not transfer to another person the right to return the lease deposit or provide it for the purpose of a pledge or other security.

C. On November 19, 2010, C transferred KRW 27 million among the claims for the return of the leased deposit to the Plaintiff, and notified the Defendant of the assignment of the claim by means of content-certified mail on November 24, 2010, and on the same day, C sent the notification to the Defendant.

[Ground of recognition] Facts without dispute, Gap evidence Nos. 1, 2, and 3, the purport of the whole pleadings

2. Determination of the parties' arguments

A. Since the Plaintiff did not know that there exists a special agreement prohibiting transfer of the claim for the return of the lease deposit by C, the Defendant asserts that C is obligated to pay KRW 27 million out of the lease deposit amount to C to the Plaintiff. On the other hand, the Defendant asserted that the Plaintiff could not respond to the Plaintiff’s claim because the Plaintiff knew or was unaware of the existence of a special agreement prohibiting transfer of the lease deposit claim.

B. In the event that a third party takes over a claim from a creditor, the obligor may set up against the assignee who is aware of the existence of the special agreement prohibiting the assignment of the claim, or the assignee who is grossly negligent in not knowing the existence of such special agreement. The gross negligence here refers to the gross negligence, even if it does not pay considerable attention to the extent required of ordinary persons, if it is not done so, it is difficult to easily know the existence of such special agreement, but is not paid such attention.