Rousseau (1989) is known for her study that redefined the psychological contract and made quantitative analysis of it possible. This study clarified the concept of the psychological contract by contrasting it with the implied contract. Following this study, studies and conceptual expansion of the psychological contract have progressed; however, even Rousseau herself has stopped mentioning the implied contract. However, the implied contract, an objectively observable reciprocal pattern, is practically a substantial contract and is highly likely to be considered as a contract by courts, even if it is not stipulated in writing. Furthermore, a violation of the implied contract results in a termination response, which confirms its existence even more clearly. Therefore, this study summarizes anew the differences between the psychological and implied contracts and defines the phenomenon that should be classified as the implied contract.