PURPOSE: To prevent blocking from being caused on a transfer buffer by controlling the timing of packet transfer to an input packet transfer path by a received packet transfer control part with an answer frame from a packet switching control part.

CONSTITUTION: The received packet transfer control part 10 when detecting its answer frame sends a packet out to the input packet transfer path 2 according to an indication. All buffers 4 which are connected to the transfer path 2 are sent the request frame, and checks the address information at the head of the packet and receive and store packet information addressed to transmitted packet transfer control parts 11 to which the buffers are connected into the buffers. Other buffers 4 do not input the packet. Each control part 11 inquires the respective buffers 4 through output packet transfer paths 3 which are connected at a specific period and sends packets when the packet is stored.