Recent rapid growth of information environment such as the Internet makes it easy for us to get vast information. On the other hand, "information overflow" is becoming a serious problem. That is, available information resources are too much for human to utilize, and sometimes confuse human's activity. In this paper, we propose a new mechanism for discovering a similarity among documents. This mechanism is called "Fish Eye Matching", which generates a feature vector from a text dynamically based on a concept structure derived from an electronic dictionary such as EDR. Using this concept structure, this mechanism can use semantic relations among words, which have not been considered in existing feature vector paradigms, and reorganize information space dynamically according to users' interests. This paper also presents a prototype system for supporting information organization process based on this Fish Eye Matching method.