A wireless ad hoc network is established so that communication terminals performing random access do not interfere with one another. A radio communication device grasps the existence of a surrounding radio communication device using a predetermined method, and when a new radio communication device is detected, an authentication verification operation of the new radio communication device is performed. When the authentication is successful, the new radio communication device is registered in a neighbor connection list. If the authentication fails, it is registered in a neighbor non-connection list. As a result, the wireless ad hoc network can be established without having the radio communication devices sharing the same space interfering with one another.