When a first mode (with-SOF mode) has been set, data transfer is performed while SOF packets are transferred at frame periods, and when a second mode (non-SOF mode) has been set and also non-periodic (bulk) transfer is being performed, the periodic transfer of SOF packets is disabled and non-periodic data is transferred. If there is no non-periodic data to be transferred, a SOF packet is transferred in the frame period, even if the second mode has been set. During host operation with USB on-the-go (OTG), pipe regions are allocated to the packet buffer, and non-periodic data is transferred automatically to or from end points while the periodic transfer of SOF packets is disabled. When all of the automatic transfer instruction signals of the pipe regions are inactive, SOF packets are transferred periodically even if the second mode has been set.