Almost conventional search engines employ centralized architecture. However, such an engine is not suitable for fresh information retrieval because it spends a long time to collect web pages by using a web robot (or crawler). In the other hand, there are some distributed search engines such as Harvest and so on. However, these distributed search engines are not also enough in order to update in a very short time, e.g. a few minutes. In this paper, we propose a distributed information retrieval systems, called Cooperative Search Engine (CSE), in which multiple distributed local search engines communicate with each other in order to realize a whole global search engine. A local search engines has own index database and can update quickly. In addition, they cooperate each other in order to reduce their workload. In this paper, we describe the structure and behavior of CSE, and its efficiency.