To obtain a bus transfer device capable of efficiently executing DMA transfer of a packet transmitted/received by one or a plurality of NIC ports at high speed on a PCI bus.

A DMA framer 112 executes the DMA transfer of a DMA frame, to which frame information including a data length for identifying the NIC ports 120-12n handling a packet is added, to the packet temporarily held in a packet buffer 113. The DMA framer 112 extracts a packet from the DMA frame including the packet, which is DMA-transferred via the PCI bus 104 and destined to the NIC ports 120-12n, and transmits it to the NIC ports 120-12n. When the DMA transfer is finished, an interrupt factor presenting device 114 presents an interrupt factor of an interrupt signal asserted by a PCI bus interface 111.