In a method for monitoring servers including destination servers for failure: definition-for-monitoring information including servers to be monitored, a monitoring procedure including a definition of a monitoring packet used in diagnosis of the servers to be monitored, and a criterion for determining normality of the servers to be monitored is generated and stored for each destination server; the monitoring packet is transmitted to each server to be monitored, in accordance with the definition-for-monitoring information; and it is determined that the server to be monitored is faulty and delivery of request packets to one of the destination servers corresponding to the server to be monitored is not allowed, when no response is returned from the server to be monitored, or when a response packet received from the server to be monitored does not satisfy the criterion.