Reputation, as a part of collective systems of beliefs and opinions about people and things, is an important criterion to judge other people. With the rise of Web 2.0, reputation has gained a superior influence in large-scale online communities (Blog, SNS and etc) - which can be considered as a miniature of offline society- than it did in offline society. This can be explained by online society's unique characteristic, anonymity. The online (digital) reputation encourages contribution and provides motivation for active participation, leading to better quality of the content and to better user experience. This paper proposes reputation model in blogosphere that rely on relationship among people and activity of bloggers. We have implemented the proposed system, and we have used it to analyze the blog in Korea consisting of thousand pages. Our results show that our notion of reputation has good predictive value.