This paper reviews the concept of skill in economics and sociology in Japan and explores the methodological problems of the notion of skill. In Japan the concept of skill has been dealt with in three fields : Japanese industrial relations theory, studies of skill formation and theory of organizations. Since unions in Japan have not constructed so called “artificial skill” which is commonly seen in Europe, Japanese researchers pay attention to “genuine skill” rather than “socially constructed skill” and try to operationalize skill to obtain objective measure. Therefore the concept of skill is so narrow that it fails to represent the complexity and relational phenomenon of skill in the work process. In this paper I present more complex relations between “ggenuine skill” and “socially constructed skill” than former Japanese researchers have assumed, drawing upon literatures of the social constructionists and comparable worth. First, I examine the theoretical basis of current arguments of skill in Japan. Second, I elaborate the arguments of the social constructionists and comparable worth, focusing on the social process involved in the skill formation and the seemingly objective notion of skill. Third, I examine the validity of different approaches discussed in this paper and propose sociological directions in the theory of skill by conceptualizing the social aspects of skill in Japanese work process. I suggest that the sociology of work would benefit from greater sensitivity to preconceptions of skill. Sociological theory of skill would offer an opportunity to develop more appropriate basis for international survey of comparative industrial relations.