A. On January 22, 2007, A created a joint collateral security (hereinafter “instant collateral security”) with respect to each real estate listed in the separate sheet owned by B, which is KRW 3220,000,000, with respect to each real estate indicated in B, the obligor and the maximum debt amount of which are KRW 322,000,000, as to each real estate indicated in the separate sheet owned by B, to secure the obligation to the non-party bank.

B. On January 22, 2007, the Defendant acquired the secured debt of the instant right from the bank and completed the additional registration for the transfer of the said right to collateral, and then received dividends of KRW 3,411,874,541 as the principal and interest of the said secured debt from the auction procedure on the real estate stated in attached Tables 1 and 2 of the List Nos. 1, 209 (hereinafter “first auction”) on September 23, 2009, based on the instant collateral security (hereinafter “first auction”). < Amended by Presidential Decree No. 1,517,328,109,109, and 1,894,546,432 won in the auction procedure on the real estate listed in attached Tables 3 through 8, 2011 (hereinafter “second auction”).

C. On September 5, 2013, the Plaintiff acquired a claim amounting to KRW 500 million against A of the same bank from ADK Mutual Savings Bank, and the succeeded execution clause was served on A on September 9, 2013.

[Ground of recognition] Facts without dispute, Gap 1, 2, and 4 evidence 1, 2, Gap 3-1 to 8, the purport of the whole pleadings

2. The judgment of this Court

A. The Plaintiff’s assertion 1) : The Defendant received dividends in excess of the maximum debt amount of the instant right to collateral security at the auction procedure, thereby unjust enrichment. As such, the Plaintiff sought the return of the excess amount on behalf of the obligee A as a creditor of the joint collateral security. 2) Even if the sum of the principal and interest of the secured debt distributed to the mortgagee during each auction procedure exceeds the maximum debt amount, even if the sum of the secured debt amount apportioned to the mortgagee during each auction procedure exceeds the maximum debt amount, the excess amount is not established, and even if not, the damage is incurred therefrom.