The wireless LAN device 10 includes a packet transmission controller 102 having the function of transmitting a DHCPDISCOVER packet from a LAN switch 130 to wired devices and the function of causing an RF device to transmit a Probe Request packet to other wireless LAN devices through an antenna 150; a first operation controller 104 that can set the wireless LAN device 10 in the operating mode where the wireless LAN device 10 can operate as an access point, when the wireless LAN device 10 receives DCHPOFFER packet; and a second operation controller 106 that can set the wireless LAN device 10 in the operating mode where the wireless LAN device 10 can operate as a client, when the wireless LAN device 10 receives a Probe Response packet.