In order to track a mobile body in an efficient manner, a server collects passage trail information relating to a mobile body to be tracked from a camera provided in an information-centric network to thereby track the mobile body. Specifically, the server transmits a request message which designates a search area and a search period to the information-centric network, requesting the information-centric network to provide passage trail information relating to the mobile body, the passage trail information being acquired by the camera; receives a response message including the passage trail information; and collects the passage trail information associated with the search area and the search period designated by the request message to thereby generate tracking information.