This paper is a study on the design and implementation of cooperative monitoring agent using mobile agent for educational portal site. Generally educational portal sites have many addresses of teachers homepage. Therefore, portal site has a very difficult task with maintaining a consistent address of site and administration of portal is impossible while to be on the search for all dead sites. In order to overcome this problem, we designed and implemented a mutual cooperative monitoring agent in order to filter off dead site using mobile agent. The monitoring agent applies at Korean educational portal site (KEPS) for elementary student and makes an experiment efficient. Finally a cooperative mobile agent is compared with a stationary monitoring agent.