是否為勞動契約上之雇主，在勞雇之間產生爭議時，影響到勞工得向何人請求確認勞動契約上受僱地位，以及請求給付工資。理論上，雇主限於勞動契約上所明示的當事人。不過，隨著經濟發展，經營組織產生變遷，僱用模式變得多元化，因此若僅使契約上的雇主對於勞工負責任，有時會欠缺妥當。在此情形之下，學理上常見採用法人格否認理論，來擴張雇主之概念。近年來在勞動法案件，也有法院判決採用此理論。因此，此理論在勞資間的糾紛如何適用，實有進一步檢討之必要。有鑑於此項理論在日本已有許多討論，也受到該國法院實務的援用。因此，本文考察法人格否認理論在日本學說與實務的相關發展，並整理出其特徵，以作為我國學說與實務進一步討論與運用之參考。 When the issue of whether or not being an employer in a labor contract becomes a dispute between employees and employers, it influences the issue concerning whom employees should sue to confirm the employed-status in the labor contract. In theory, only the party written or expressed in the labor contract can be the employer. However, as the economy grows and organizational management changes, employment patterns also become diversified. It would be improper to make the only employer in the written labor contract be liable to the employee. In this situation, the study makes use of the doctrine of piercing the corporate veil to extend the concept of the employer. Although several judgments denied such a doctrine to be used in the case of the Labor Act in recent years, the Taiwan Supreme Court declared the following: To prevent the employer from dodging the law concerning the improper dismissal by the state of the juridical person, and eliminate the problem of abusing the right of dismissal from the employer, it should also concern the other juridical person who has ＂the same single entity＂ with the ＂original employer＂ and also has no adequate work to help the employee to settle down. Under these circumstances, in order to understand how to apply the doctrine of piercing the corporate veil to resolve the dispute between the employer and employee, it is necessary to undertake further examination. In light of the fact that this doctrine has been widely discussed in Japan for years and many courts also abide by the verdicts concerning it in Japan, this study will examine the development of the doctrine of piercing the corporate veil in the academy and its application in courts, as a reference of the academic discussion and its application in courts in Taiwan.