The plaintiff's claim is dismissed.

Litigation costs shall be borne by the plaintiff.

1. Facts of recognition;

A. On September 4, 2015, the Defendant: (a) concluded a contract with the Plaintiff on September 4, 2015, for the construction of a new building complex C (hereinafter “instant building”); (b) “The construction work on September 4, 2015 on the date of commencement; (c) the construction work on February 29, 2016 on the scheduled date of completion; (d) the construction work on February 29, 2016; (e) the amount of KRW 1,705,000,000 (including value-added taxes); and (e) the delayed reward rate of KRW 1/1,000 (hereinafter “the primary contract”); and (e) included electrical construction and fire-fighting construction in the scope of the primary contract.

B. As to the first contract on February 20, 2016, the Plaintiff and the Defendant entered into a contract with “the date of commencement, September 4, 2015, the scheduled date of completion, May 10, 2016, and the construction cost to KRW 1,650,00,00 (including value added tax)” (hereinafter “the second contract”), and the electrical construction and fire fighting construction were included in the scope of construction works under the second contract, the same as the first contract.

(c)

On July 19, 2016, the Plaintiff completed the instant construction project under the second contract. The Defendant paid the Plaintiff KRW 1,671,00,000 in total to the Plaintiff eight times from September 17, 2015 to September 9, 2016, and obtained approval for the use of the instant building on July 19, 2016.

(d)

Since then, the Defendant confirmed that the Plaintiff remitted KRW 1,671,00,000 to the Plaintiff in excess of the construction cost stipulated in the secondary contract, and demanded the return of KRW 21,00,000 that was paid in excess to the Plaintiff (= KRW 1,671,00,000 - KRW 1,650,000). On January 12, 2017, the Plaintiff returned KRW 21,000,000 to the Defendant on January 12, 2017.

[Reasons for Recognition] Facts without dispute, Gap evidence Nos. 1 through 5, Eul evidence Nos. 1 through 3 (including numbers, hereinafter the same shall apply) and the purport of the whole pleadings

2. The plaintiff's assertion

A. The second contract provides that the construction cost of this case, including electrical construction and fire fighting construction, shall be determined, but in fact, the defendant bears the electrical construction cost and the fire fighting construction cost.