To relay a packet data to other wireless access point by ad hoc communication means in case abnormality of a communication state on the cable LAN side is detected.

In case abnormality of a communication state on the side of cable LAN 5 is detected by an abnormality detecting part 17, an ad-hoc mode communication control part 14 relays a packet data received from a wireless LAN terminal belonging to an own wireless access point 1, to other wireless access point by ad hoc communication means with no intervention of the cable LAN 5; and a packet data received from other wireless access point and addressed to the wireless LAN terminal belonging to the own wireless access point, to the wireless LAN terminal.