An increase in communication load in a network due to increasing messages for requesting information is suppressed. When a message for requesting information and a response message thereto are sent and received between a communication device (N1-Nn) that is an information requester and an information provider (Nx) on a network (NW) via a communication device (1), the communication device (1) stores the information acquired from the response message in a response information storage section (4), and when any communication device requests at least part of the same information, a control section (5) creates a response message including the requested information and responds.