A data distribution control device (10) which is disposed on a transmission line between a transmission device (C1) requiring a transmission acknowledge to transmitted data and a reception device (C2), and which can perform a transfer processing for transferring data from the transmission device (C1) to the reception device (C2) with transmission delay of a circuit (2) set smaller than that of a transmission delay circuit (3), and a return processing for producing a transmission acknowledge to the transferred data to return it, wherein a distribution control unit (16) judges whether or not data transmitted by the transmission device (C1) is a delay-dependent protocol, and, only when judged to be the delay-dependent protocol, has a return processing for transmission acknowledge performed. |