A. The plaintiff is a juristic person running an information and communications construction business, and the defendant is a person running an information and communications construction business in the name of "C" from the fifth floor of the Bupyeong-gu Incheon Bupyeong-gu B building, Incheon (hereinafter "computer 200 size").

B. From September 2014 to December 2012, 2014, the Plaintiff: (a) had been engaged in the construction of electric, communications, fire fighting, and scream guard (hereinafter “instant construction”); and (b) had commenced the operation of the instant scream guard on December 2, 2014.

The Plaintiff and the Defendant did not prepare a written construction contract at the time of the instant construction work.

[Reasons for Recognition] Facts without dispute, purport of whole pleading

2. The parties' assertion

A. The Plaintiff and the Defendant did not specify the construction cost at the time of the instant construction work. However, according to the quotation prepared by the Plaintiff, the instant construction cost is KRW 32,858,775, and the Defendant adjusted at the Defendant’s request and determined KRW 31,018,775 as the final construction cost.

25,918,775 won calculated by subtracting KRW 5,100,000 from the above amount from the defendant shall be claimed as the balance of construction price.

B. The Plaintiff calculated the unit price of KRW 80,000 per initial computer, and as a total of KRW 16,000,000 per initial computer, the instant construction was conducted during the period of the construction. The construction price paid by the Defendant is KRW 9,494,00.

In addition, since the defendant spent 15,576,00 won as the repair of defects and the cost of finishing the construction work performed by the plaintiff, the above cost should be deducted from the construction cost of this case.

3. Determination

A. According to the written evidence Nos. 1, 5-8 (proof of contents received between the plaintiff and the defendant) of this case, the plaintiff and the defendant did not specify the construction cost at the time of the instant construction work.

In addition, each of the above evidence, Gap evidence Nos. 14, 15, and Eul evidence No. 11 (written estimate prepared by the plaintiff) is insufficient to recognize that the construction price of this case reaches KRW 31,018,775, and there is no other evidence to acknowledge it.

However, evidence Nos. 1 and 6-