B. Whether a special agreement is concluded to waive the lessee’s right to claim reimbursement of the beneficial cost, where the lessee returns the leased object to its original state with the burden of all the expenses.

(c) Whether an liability for damages caused by an illegal possession occurs where a lessee has continuously occupied the object of lease by exercising a right of defense of simultaneous performance after the lease contract is terminated;

B. In a case where a lease contract is concluded, the lessee may rebuild or alter the part of the building which is the leased object under the approval of the lessor, but if the lessee agrees to restore the leased object to its original state with the burden of expenses incurred by the lessee, it is reasonable to deem that the lessee has given up the right to demand reimbursement of all kinds of beneficial expenses incurred by the leased object in advance

C. Since a lessee’s obligation to return the leased object arising from the termination of a lease agreement and the obligation to return the remaining security deposit, which deducted the lessor from the lessor’s default on payment, is in a simultaneous performance relationship, if the lessee continuously occupied the leased object by exercising his/her right of defense of simultaneous performance even after the termination of the lease agreement, the lessee’s possession of the building cannot be deemed an illegal possession. Therefore, the lessee’s liability for damages arising from an illegal possession should not be deemed to have arisen immediately

A. On the first ground for appeal

The court below rejected the plaintiff's assertion that "the lease contract of this case was terminated by the plaintiff's declaration of termination on October 5, 1991" is not erroneous in the misapprehension of legal principles as to mistake of facts and termination of lease due to violation of the rules of evidence, such as theory of lawsuit, and there is no reason to discuss

B. On the second ground for appeal

According to the reasoning of the judgment below, the court below held that the non-party who operated a simplified restaurant business in the part of the building of this case, which is a leased object, paid 4,200,000 won directly to the "Plaintiff" from October 1992 to March 1993.

However, examining the evidence admitted by the court below in light of the records, the above facts are deemed to have been based on the testimony of the non-party to the witness of the court below, and when considering the testimony of the above non-party, the counter-party who directly paid the above rent is the defendant (the counter-party to the plaintiff, hereinafter the defendant), and in calculating the overdue rent from the lease deposit of 22,00,000 to the lease deposit of this case which the defendant is liable to return to the plaintiff, the above rent of 4,20,000 won is deducted from the rent already paid to the defendant, in calculating the overdue rent from the lease deposit of this case which is deducted from the lease deposit of 22,00,000 won, the above rent of the above rent of this case is included in the rent already paid to the defendant. Thus, it is evident that the above non-party's statement as "the counter-party who directly paid the above rent is a simple clerical error of the defendant, and there is no reason to conclude any error of mistake of facts due to the

C. On the third ground for appeal

The court below rejected the plaintiff's assertion that "the agreement was reached between the plaintiff and the defendant on the compensation of the plaintiff's business losses due to the delay in the completion inspection of the building of this case," and there is no error of misconception of facts such as the theory of lawsuit, and there is no ground

D. On the fourth ground for appeal

Article 626 (2) of the Civil Code provides for a lessor's duty of repayment refers to the cost invested by the lessee in order to increase the objective value of the leased property (see Supreme Court Decision 91Da8029 delivered on October 8, 191). The court below held that the signboard of this case is merely a facility attached to the Plaintiff for the operation of a simple restaurant in the building of this case and it is difficult to regard it as an increase in the objective value of the above part of the building, and that the signboard of this case cannot be considered as a beneficial cost because there is no increase in the value of the building, and therefore it is reasonable in accordance with such legal principles, and there is no error of misunderstanding of facts or misunderstanding of legal principles as to the theory of lawsuit, and therefore there is no ground to

E. On the fifth ground for appeal

Under the agreement with the defendant, the court below recognized the fact that the plaintiff invested the construction cost of the building of this case, which is the leased object, into the boiler facility construction work, and the plaintiff, the lessee, at the time of concluding the lease contract of this case, may rebuild or alter the building of this case under the approval of the defendant, who is the lessor, but when ordering the lessor to restore the leased object, the lessee shall bear all the expenses and restore the leased object to its original state. In light of the records, the court below's above fact finding is acceptable, and there is no error of mistake of facts such as the theory

In addition, if the Plaintiff agreed to return the building portion of this case to the lessor, as at the time of the original adjudication, to restore it to its original state, it is reasonable to deem that the Plaintiff is a special agreement to waive in advance the Plaintiff’s right to demand reimbursement of all kinds of beneficial costs incurred on the leased object. Accordingly, the lower court’s rejection of the Plaintiff’s right to demand reimbursement of the construction cost of the boiler facilities in the same purport is justified, and there is no misapprehension of the legal principle as to the waiver of the

2. We examine the defendant's grounds of appeal.

A. On the first ground for appeal

The court below's decision is justified in finding and judged that the plaintiff continued to possess the leased building portion of this case from November 1991 to March 1992, but it failed to conduct a simple restaurant business and therefore failed to use and make profits in accordance with the original purpose of the lease contract. There is no error of law of misconception of facts and violation of the right of disposal due to violation of the rules of evidence, such as theory of lawsuit, and there is no reason to discuss.

B. On the second ground for appeal

Since the duty to return the leased object that occurred upon the termination of the lease agreement and the duty to return the remaining security deposit after deducting the lessor from the overdue rent, if the lessee has continuously occupied the leased object by exercising his/her right to defense of simultaneous performance even after the termination of the lease agreement, possession of the leased object cannot be deemed an illegal possession, and thus, it shall not be deemed that the lessee has been liable for damages arising from illegal possession (see Supreme Court Decision 89Da2498 delivered on October 27, 1989). Accordingly, as discussed in the lawsuit, even if the court below examines the Defendant’s statement on the date of pleading, it is reasonable that the Plaintiff’s liability for damages was recognized and the Defendant cannot be deducted from the leased security deposit, and the Plaintiff’s right to claim damages equivalent to the rent due to the Plaintiff’s possession of the leased object from the expiration of the lease agreement to the name city of the leased building after the expiration of the lease agreement, and there is no error in the misapprehension of the legal principles as to the Plaintiff’s right to claim compensation for damages.

3. All appeals are dismissed, and the costs of appeal are assessed against each party. It is so decided as per Disposition by the assent of all participating Justices.

Justices Kim Jong-sik (Presiding Justice)