In information retrieval of web pages, we usually use search engines. A conventional search engine has the problem that the update interval is very long because it is based on centralized architecture, which collects documents by using robots. So, we have developed a distributed search engine, cooperative search engine (CSE) in order to reduce the update interval. In CSE, a global search engine is constructed with multiple meta search engines, which hide each local search engine in each Web site. CSE can make the update interval very short by indexing on each web site. In this paper we describe the framework of CSE and its efficiency.