A. The Plaintiff is the owner of Seosung-si C Apartment 618 Dong 1402 (hereinafter “instant apartment”), and the Defendant is running an artificial complex construction business with the trade name “D”.

B. On March 26, 2015, the Plaintiff and the Defendant concluded the instant apartment construction contract (hereinafter “instant construction contract”).

C. On March 26, 2015, the first Defendant issued a written estimate of KRW 8,8110,00 (excluding value-added tax) to the Plaintiff, and thereafter, issued a written estimate of KRW 83,886,00 (excluding value-added tax) to the Plaintiff and the Defendant under the name of the Plaintiff and the Defendant.

Until May 2015, the Plaintiff paid KRW 65 million to the Defendant as the instant construction cost.

E. On May 27, 2015, the Defendant issued a written estimate of KRW 118,98,00 (excluding value-added tax) to the Plaintiff. The Defendant, on May 30, 2015, issued a written estimate of KRW 88,017,360 (excluding value-added tax) to the Plaintiff.

F. On May 30, 2015, the instant construction was suspended due to disputes between the Plaintiff and the Defendant regarding the instant construction and amount, etc.

G. Since then, the Plaintiff completed the interior construction of the instant apartment through another company.

[Ground of recognition] Facts without dispute, Gap evidence Nos. 1 through 3, Eul evidence No. 6, the purport of the whole pleadings

2. The parties' assertion

A. Although the Plaintiff paid KRW 65 million to the Defendant, the part of the construction work that the Defendant proceeded cannot exceed KRW 20 million, the Defendant is obligated to return unjust enrichment to the Plaintiff.

B. The Defendant’s actual expenses incurred in the instant work are KRW 42,937,180 in the account; KRW 6.5 million in cash; KRW 535,00 in the purchase cost in remote areas remaining in stock; KRW 50 million in total; KRW 2/3 of the work progress; KRW 5,000 in the amount of labor cost paid by the Plaintiff; KRW 5,000 out of KRW 65,00 in the amount of value-added tax paid by the Plaintiff.