This article reviewed recent four theories about the self. Self-assessment theory (Trope, 1975) assumes that a person is motivated to assess his/her own ability and that he/she selects tasks to reduce uncertainty of his/her ability level. Self-evaluation maintenance model (Tesser & Campbell, 1982) presumes that a person is motivated to maintein self-evaluation positively and thereby change perceptively or actually one of following three factors; other person's closeness, performance, task relevance to self. Self-serving bias (Bradley, 1978) means that one attribute success to internal factors and failure to external factors. Self-handicapping strategy (Jones & Berglas, 1978) is to give handicaps to the self beforehand and it increases the possibilities that self-serving bias takes place. These four theories have been respectively supported by several studies. These four theories can be classified into two categories; one is related to assess the self and the other is related to protect or to enhance the self. When we consider the appearant order of the phenomena relevant to the self, self-assessment is assumed to be the prestage of self-protection or self-enhancement.