Abstract: An object of the present invention is to set a wireless LAN communication parameter with respect to an appliance connected to an in-home network smoothly and easily. Prior to purchasing an appliance, a user registers an in-home network in a center server, and receives a user ID and an e-mail address. Thereafter, when the user purchases an appliance from a vendor by presenting his/her own user ID, a user ID and a device encryption key of the appliance are transmitted from the vendor to the center server. The center server transmits the received information to an e-mail address (home server) of the user ID. The home server searches for a corresponding appliance in an ad hoc mode using the received device encryption key. At this time, when the purchased appliance has already been on the network, communication is established, and a user encryption key (wireless communication parameter) is given from the home sever to the appliance.