Abstract: It is intended to improve the efficiency of request retransmission. A high-speed serial interface block is provided which enables split-transaction communication performed through the issuing of a response from a completer to a request issued by a requester. The high-speed serial interface block mentioned above is provided with a reception butter for retrieving received data and with a control unit for causing execution of a process which is performed in the case where there is no response from the completer mentioned above within a predetermined time when the reception buffer mentioned above has overflown. When the reception buffer mentioned above has overflown, a process of issuing a time out even within a prescribed time for time-out determination is allowed to improve the efficiency of request retransmission.