1. The plaintiff's appeal is dismissed.

2. The costs of appeal shall be borne by the Plaintiff.

The purport of the claim and appeal is the purport of the appeal.

1. On January 4, 2014, the Plaintiff asserted that the Plaintiff entered into an employment contract with the Defendant and paid 2.7 million won of wages, allowances, and 300,000 won of retirement allowances each month in accordance with the employment contract, which was employed as an engineer for the Defendant. The Defendant demanded the Plaintiff to pay a separate retirement allowance after retirement from February 2016 and paid 6.4 million won to the Defendant. As long as the Defendant received a retirement allowance after retirement, the Plaintiff is obligated to return 7.8 million won of retirement allowances paid in advance during the period of employment (=30,000 won x 26 months) to the Plaintiff as unjust enrichment.

2. In light of the fairness, it is reasonable to view that the employee should return to the employer the money in the name of the retirement allowance received by the employee as unjust enrichment, unless the validity of the payment of the paid retirement allowance is recognized as well as the validity of the payment of the paid retirement allowance even though the employer actually paid the employee the money in the name of the retirement allowance.

However, considering the legislative intent of the retirement allowance system as mandatory law, the above legal principle can only be applied on the premise that there is an actual retirement allowance installment agreement between an employer and an employee.

Therefore, even though the pertinent agreement entered into between an employer and an employee is merely a determination of the amount of wages, if the employer took the form of a retirement allowance installment agreement to evade the payment of retirement allowances, such legal doctrine cannot be applied.

(2) In light of the aforementioned legal doctrine, the Plaintiff and the Defendant did not appear to have agreed on a retirement allowance installment agreement between the Plaintiff and the Defendant solely on the sole basis of the statement on the health account and the evidence No. 1 as to the instant case in light of the foregoing legal doctrine. Therefore, it is difficult to deem that there existed a substantial retirement allowance installment agreement between the Plaintiff and the Defendant solely on the sole basis of the Plaintiff’s assertion.

Therefore, effective.