The judgment below is reversed, and the case is remanded to the Incheon District Court Panel Division.

The grounds of appeal are examined.

1. According to the reasoning of the lower judgment, the Plaintiff’s disciplinary action against the Defendant, who is a worker, around December 2015, paid KRW 3,996,810 to the Defendant on the 18th day of the same month as the pre-determination allowance, and thereafter, the National Labor Relations Commission decided that the dismissal constituted unfair dismissal. The Defendant was reinstated on August 1, 2016, and the Plaintiff paid the full amount of wages from the time of the dismissal to the time of reinstatement to the time of the reinstatement. The Defendant returned the retirement allowance paid to the Plaintiff at the time of the said dismissal.

Based on each of the above facts, the lower court determined that the Defendant should return the amount equivalent to the pre-determination allowance to the Plaintiff as unjust enrichment on the ground that, if the wages during the period of dismissal were to be paid due to the invalidity of the dismissal, the employee would lose the legal cause of holding the pre-determination allowance.

2. However, the lower court’s determination is difficult to accept for the following reasons.

In accordance with the main sentence of Article 26 of the Labor Standards Act, when an employer fails to make an advance notice of dismissal 30 days prior to the dismissal of an employee, the advance notice allowance to be paid to the employee is the amount that should be paid regardless of whether the dismissal is valid, and even if the dismissal is invalid as it constitutes unfair dismissal, it cannot be deemed that there is no legal ground to receive

(see Supreme Court Decision 2017Da16778, Sept. 13, 2018). Nevertheless, the lower court erred by misapprehending the Supreme Court precedents stipulated under Article 3 subparag. 2 of the Trial of Small Claims Act, which held that the Defendant should return the amount of the pre-determination allowance for dismissal as unjust enrichment solely on the grounds stated in its holding.

3. Therefore, the lower judgment is reversed, and the case is remanded to the lower court for further proceedings consistent with this Opinion. It is so decided as per Disposition by the assent of all participating Justices on the bench.