The judgment of the court below is reversed, and the case is remanded to the Seoul Central District Court Panel Division.

The grounds of appeal are examined.

1. The non-performance of debt under Article 742 of the Civil Act is established only when the payer voluntarily pays the debt with knowledge of the absence of the debt, and was aware of the non-performance

(6) On December 14, 1992 and December 20, 1996, the lower court’s reasoning and records reveal that: (a) the Defendant, upon entering the Plaintiff Company on October 31, 2013, paid additional KRW 10,485,879 won to the Defendant on October 31, 2013; and (b) the Defendant, upon receiving a warning of the Defendant on March 28, 2013, paid additional KRW 10,485,879, which was immediately before the Plaintiff Company’s retirement pay; and (c) the Defendant, upon receiving a warning of the Defendant on March 25, 2013, paid additional KRW 20 to the Defendant based on his/her own free will (see, e.g., Supreme Court Decisions 91Da17917, Feb. 14, 1992; 95Da52222, Nov. 20, 2013; and (d) the Defendant’s additional amount of retirement pay to the Defendant for three months immediately preceding three months.