1. The plaintiff's appeal is dismissed.

2. The costs of appeal, including the part arising from the supplementary participation, are all assessed against the Plaintiff.

1. The reasoning of the judgment of the court of first instance concerning this case is as follows, except for adding the following judgments as to the plaintiff's argument of the first instance related to the existence of interest in the lawsuit between the 6th and 14th decision of the court of first instance, and thus, it is consistent with Article 8(2) of the Administrative Litigation Act and the main text of Article 420 of the Civil Procedure Act.

【Supplementary Judgment】

The plaintiff asserts that the plaintiff still has a benefit of action to claim the invalidity of unfair dismissal and the maintenance of employment relationship against the intervenor as long as the intervenor still has concluded a contract with the Korea Railroad Corporation and the Seoul metropolitan area cleaning service contract and provides cleaning service.

On March 31, 2016, the Intervenor notified the Plaintiff of the termination of the labor contract according to the cleaning service contract with the Korea Railroad Corporation and the Plaintiff on April 30, 2016, comprehensively taking account of the descriptions of Gap evidence No. 11, Eul evidence No. 11, Eul evidence No. 16 and the fact-finding results with respect to the President of the Korea Railroad Corporation.

It can be recognized that the cleaning service of rolling stock in the Seoul Metropolitan Area continues to be provided from April 1, 2016 to the time of the closing of argument in the trial.

However, as seen earlier, in order to promote employment stability of workers belonging to existing service enterprises in order to promote the Korea Railroad Corporation according to a technical negotiation contract with the participant, the content of the obligation to succeed to employment should be borne by the new service enterprise to succeed to the employment of workers belonging to the existing service enterprises actually invested for the provision of the relevant service. As such, the participant who was ordered to provide the service of cleaning rolling stock from April 1, 2016 to the Korea Railroad Corporation in accordance with the service contract with the Korea Railroad Corporation as of March 31, 2016.