"Sharing norms" has rarely been studied directly though it is one of the most important key-concepts in self-effacement research. The present study examined the effects of sharing norms on individual behavior by operationalizing the degree thereof regarding self-effacement. Two levels of sharing were measured : in a personal network and in a social system. It was predicted that both levels of sharing would be positively correlated with individual self-effacement behavior. A mail survey covering 12 local communities in Japan was conducted. The results showed that people engage in self-effacement more frequently when 1) positive evaluation and behavior regarding self-effacement were shared in their personal network and 2) behavior regarding self-effacement was shared in the communities where the respondents live. Sharing in a personal network was also correlated with individual attitude toward self-effacement. We discussed the differences of the roles that sharing in a personal network and social system plays in terms of self-effacement.