1. The reasoning of the lower judgment reveals the following facts.

(1) On May 23, 2011, the Defendants transferred 120,700 shares of D Co., Ltd. (hereinafter “D”) owned by the Defendants to the Plaintiff and KRW 2,020,00,000 in total of D’s bonds and borrowings against D’s FF associations and Korea Housing Guarantee Co., Ltd.

(2) At the time of the above transfer, the Defendants prepared and ordered a statement of performance of the duty (hereinafter “each of the instant notes”) to the effect that “If any defect or problem arises in the construction work jointly and severally guaranteed by D to another company as of the above transfer date, the Defendants jointly and severally liable and immediately resolved.”

(3) Meanwhile, on August 8, 2007, D constituted a joint contractor with H Co., Ltd. (hereinafter “H”) and contracted the instant construction work with the Korea Highway Corporation in the amount of KRW 1,300,000,000. The said contract stipulates that the members of the said joint contractor shall be jointly and severally liable for the instant construction work.

(4) Around June 2008, D maintained the joint performance method in relation to H and the ordering office. In its inside, H agreed to receive only the agreed installment payment that includes construction profits, industrial accident and employment insurance premiums, and settlement amount, etc.

(5) Following the commencement of rehabilitation procedures for H on May 10, 2012, the said contract was terminated on or around July 20, 2012, and the FF Union, which guaranteed the duty to perform the construction works of the said joint supply and demand company under the said contract, had K Co., Ltd. guarantee and execute the instant construction works, paid the construction cost of KRW 9,549,100,000, and the FF Union thereafter claimed KRW 724,162,799 in total from July 4, 2013 to April 9, 2014.

2. The court below held that the Corporation of this case jointly and severally guaranteed the performance of H, a joint contractor member of D.