Referring to FIG. 6, the configuration of packet transfer device 4 includes: CPU 41, memory 42, packet transfer program 43 that is stored in a memory device such as memory or a hard disk, transmitter-receiver 44, W-CDMA interface (W-CDMA I/F) 45, WLAN interface (WLAN I/F) 46, network interface (network I/F) 47, and transfer setting database (transfer setting D/B) 48 that is stored in a memory devi