A control apparatus controls information exchange among portable terminals which perform wireless communication via a communication network. A unit accepts a specific information-provision request from a first portable terminal. A unit determines a prescribed area based on the accepted information-provision request. A unit sends the information-provision request to a second portable terminal in the prescribed area. A unit accepts a response to the information-provision request from the second portable terminal. A unit sends the response to the information-provision request to the first portable terminal.