An apparatus for and method of acquiring an address in a Dynamic Host Configuration Protocol (DHCP) environment in a wireless LAN. The method includes: sensing that a mobile node has moved from a first network to a second network; transmitting a frame requesting association with the second network to an access point managing the second network after sensing that the mobile node has moved from the first network to the second network; and receiving a message containing an address assigned to the mobile node from the access point having received the transmitted frame. Accordingly, the mobile node can promptly acquire an IP address without an additional request.