The purpose of this paper was to discuss the locus of behavioral norms and what one "ought to do", two elements thought to be central to the conceptualization of social norms. With reference to this, two research questions were probed : 1) Do social norms constitute our inner regulation of behavior, or are they external standards held by group members?; and 2) Where is the standard for what one "ought to do" attributed to? Arguments between the two explanation for the locus of norms, i. e., "inner regulation" and "external standard", were offered, and this review concluded that social norm presuppose sociability, but that the internalized function was indispensible in decision making. In discussing the notion of what one "ought to do", this paper examined two aspects of social norm based on Cialdini, et al. (1991). In this process, we defined two forms of "ought to do" from the perspectives of generally desirable behavior, and behaviors particular to a given situation. Finally, from these discussions, we offered some future directives for social norm research.