1. A data communication control apparatus used by a communication apparatus in a network communicable with a repeater which relays target data wirelessly exchanged between mobile terminal devices, the data communication control apparatus comprising: a database unit that holds first search information which associates a terminal identification numeral of the mobile terminal device with location information on the repeater as well as second search information which associates the terminal identification numeral of the mobile terminal device with an address in the network; a first updating unit that receives from the repeater latest location information on the mobile terminal device and updates the first search information based on the latest location information; forwarding units that receive from the network the target data and a destination terminal identification numeral thereof, search destination location information associated with the destination terminal identification numeral by referring to the first search information, and forward the target data to the repeater associated with the destination location information; and a correcting unit that receives from the network the target data and a departure terminal identification numeral thereof, searches a first departure address associated with the departure terminal identification numeral by referring to the second search information, and corrects the second search information when the first departure address differs from a second departure address that has already been assigned to the target data.