B. Whether the lessee is obliged to return unjust enrichment to the lessee in a case where the lessee continuously occupied the leased building after the termination of the lease contract, but the lessee did not obtain substantial benefits from the failure to use the leased building for its original purpose (negative)

B. The gain in return of unjust enrichment on the ground that the benefit without any legal ground refers to the substantial benefit, so it cannot be deemed that the gain accrued if the building was occupied without any legal ground even if it was not used or profit-making. Thus, even after the termination of the lease contract, if the lessee continuously occupied the leased building part in order to refuse the return of the object by exercising the right of defense of simultaneous performance after the termination of the lease contract, but there was no substantial benefit due to the failure to use or make profit-making in accordance with the original purpose of the lease contract, even if the loss incurred to the lessor, the return of unjust enrichment does

On the first and second grounds for appeal

1. After the judgment of the first instance was rendered on the instant case, the argument that the Plaintiff (Counterclaim Defendant; hereinafter “Plaintiff”) paid 2,750,000 won to the Defendant (Counterclaim Plaintiff; hereinafter “Defendant”) and the Defendant was agreed to order the store of this case to the Plaintiff is not asserted by the lower court. Thus, the Defendant cannot claim this new fact in the first instance trial and submit it as the grounds for appeal.

2. According to the statement of the second oral argument by the lower court, the Defendant did not have made an oral defense of the argument on the second oral pleading date by the lower court, and even if examining the record, it does not seem to be shaking such assertion.

3. According to the records, the plaintiff's claim as the principal lawsuit in the first instance court is paid with the amount of money by the name limit of the store in this case and the amount of KRW 2,560,000 per month from February 1, 191 to the completion date of order. The plaintiff is aware that the part of the request for order order among the first instance court winning in favor of the plaintiff and the remaining claims were rejected, and the plaintiff sought a payment of KRW 3,910,000 as the purport of appeal and affixed legal stamps. Thus, the plaintiff's modification of the purport of the claim in this part is lawful, and in this case, it cannot be said that it should be amended only by a separate document, not by the petition of appeal. Accordingly, there is no reason to discuss.

On the third ground for appeal

1. The duty to return the leased object and the duty to return the remainder of the deposit, which deducted the lessee from the lessor’s default due to the termination of the lease agreement, are in a simultaneous performance relationship. Thus, if, even after the termination of the lease agreement, the lessee has continuously occupied the leased building by exercising his/her right of defense of simultaneous performance, possession of the building cannot be deemed an illegal possession, but if any, it is natural to return it as unjust enrichment (see, e.g., Supreme Court Decisions 78Da2500, 2501, Mar. 13, 1979; 80Da1495, Feb. 10, 1981; 90Meu24076, Dec. 21, 1990).

However, since unjust enrichment in return of unjust enrichment on the ground of the benefit without any legal ground refers to the substantial benefit, it cannot be deemed that profit has been obtained if the building was occupied without any legal ground even if it was not used or profit-making. Thus, in case where the lessee continued to possess the leased building part in order to refuse to return the object by exercising the right of defense of simultaneous performance even after the termination of the lease contract, but there was no actual benefit due to the lessee's failure to use it or make profit in accordance with the original purpose of the lease contract, even if the lessor suffered loss, the lessee's return of unjust enrichment cannot be deemed to have been made (see, e.g., Supreme Court Decisions 78Da2500, 2501, Mar. 13, 1979; 81Da378, Nov. 10, 1981; 85Da42285Meu1796, Mar. 25, 196; 90Meu76, Dec. 21, 1990).

2. However, according to the reasoning of the judgment below, the court below rejected the Defendant’s assertion that there was no benefit since the Defendant used or enjoyed the instant store after the expiration of the lease period for the instant store, on the grounds that the Nonparty’s testimony by the witness of the court of first instance requested the Defendant to return only a security deposit which remains after deducting the Plaintiff from the delayed payment for eight months at the time when the lease period of the instant case expires, and the Defendant refused to comply with the request, and the Defendant’s closure of the door of the store without having any collection equipment necessary for restaurant business, such as a cooling house, a table, and a tabler, etc., but solely on such circumstance, it cannot be said that the Defendant did not fully use or profit from the use of the instant store, or that there was no benefit from the occupancy.

3. However, in light of the records, even if the testimony of the above non-party is based on the non-party's testimony, the lease contract of this case was terminated on May 30, 1989, and the defendant closed the store of this case around June 10 of the same year, and it was evident that the total amount of overdue rent of the defendant was below the lease deposit at the time when the lease relationship between the plaintiff and the defendant was terminated, and even according to the facts acknowledged by the court below, the plaintiff, a lessor, has the duty to return the remaining deposit after deducting overdue rent from the defendant at that time until that time. According to the evidence Nos. 1, the court below rejected the order of the non-party to return the lease deposit and the defense of simultaneous performance, and notified the defendant that he would return the lease deposit and take over the store of this case after the closure of the store of this case. Thus, the court below erred in the misapprehension of legal principles as to the facts that the defendant did not gain profits from the closure of the store of this case after the occupancy of this case.

Therefore, the issue is justified.

Therefore, the part of the judgment below against the defendant is reversed, and that part of the case is remanded to the court below. It is so decided as per Disposition by the assent of all participating Justices.

Justices Kim Jong-soo (Presiding Justice)