1.The judgment of the first instance shall be modified as follows:

The Plaintiff (Counterclaim Defendant) is the Defendant (Counterclaim Plaintiff) with KRW 392,686.

A principal lawsuit and a counterclaim shall be deemed simultaneously.

1. Facts of recognition;

A. From the Defendant around May 2015, the Plaintiff is the place of business of this case, 'D PC located in Incheon-gun C and 2nd floor or below'.

The term "the construction of this case" is called "the construction of this case".

B was awarded a contract in the amount of KRW 30 million.

B. The Plaintiff completed the instant construction from May 30, 2015 to June 19, 2015.

C. On June 2, 2015, the Defendant paid the instant construction cost to the Plaintiff, KRW 5 million, and the same month.

8. A total of KRW 5 million, KRW 5 million on the 12th of the same month, KRW 5 million on the 17th of the same month, KRW 6 million on the 30th of the same month, and KRW 26 million on the 30th of the same month.

【Recognition of Facts】 1, 6, and 10, the purport of the whole pleadings

2. Judgment on the principal lawsuit

A. The plaintiff's assertion is obligated to pay to the plaintiff the amount of KRW 30 million for the construction work of this case and the additional construction work cost of KRW 2 million for value-added tax of KRW 35.2 million for value-added tax of KRW 3.2 million for value-added tax of KRW 35.2 million for the remainder of KRW 9.2 million for value-added tax of KRW 3.2 million and damages for delay

B. The fact that the Plaintiff and the Defendant determined the construction cost of this case as KRW 30 million is as seen earlier.

In general, where construction cost increases due to additional construction works as stipulated in the first construction contract, the contractor should perform additional construction works exceeding the scope of the original contract in order for the contractor to claim the additional construction cost, and the contractor and the contractor should have an agreement on the payment of the additional construction cost. As to the existence of such agreement and the increased amount of the construction cost, the contractor who requested the additional construction cost must prove that the Plaintiff submitted the additional construction cost.

It is not enough to recognize that there was an agreement on the payment of additional construction cost and that there was a 2 million won of the plaintiff's assertion for additional construction cost.