1. The plaintiff's appeal and the claim added in the trial are all dismissed.

2. The costs of the lawsuit after the appeal are filed.

1. Basic facts

A. On April 3, 2013, the Plaintiff, a company engaged in a construction business, etc., entered into a contract with the Defendant on the construction work that newly constructs neighborhood living facilities and multi-household houses (hereinafter “instant construction work”) on the land of Jeju City, with the construction cost of KRW 600,00,000 (in the Ghana, the construction cost of KRW 760,00,000) and the construction period from April 9, 2013 to September 9, 2013 (hereinafter “instant construction contract”).

After that, the Plaintiff completed the construction work around December 30, 2013.

B. From April 9, 2013 to January 27, 2014, the Defendant paid the Plaintiff totaling KRW 712,00,000 to the Plaintiff. From October 11, 2013 to February 21, 2014, the Defendant directly paid KRW 60,954,000 in total to the subcontractor, including C, who performed installation works, etc. at the instant construction site.

[Ground of recognition] Facts without dispute, Gap evidence Nos. 1, Eul evidence Nos. 2, 9, 11, and 12, and the purport of the whole pleadings

2. Assertion and determination

A. The Plaintiff’s assertion 1) while continuing construction under the instant construction contract, around August 2013, at the Defendant’s request, the Plaintiff agreed to install the said additional construction work, separate from the instant construction contract, and to perform the said additional construction work. Accordingly, the Defendant has a duty to pay the Plaintiff KRW 5,100,000 in total, and KRW 25,100,000 in the additional construction cost, including the construction cost of Ireland and the installation of the said additional construction contract. Even if the said additional construction work is not acknowledged, the Plaintiff completed the said additional construction work, separate from the instant construction contract, and the Defendant obtained profits equivalent to the said additional construction cost without any legal grounds.

Therefore, the Defendant’s unjust enrichment amounting to KRW 30,100,000,000 for additional construction cost to the Plaintiff.