A communication apparatus and a communication method are provided by which an upper network including a plurality of network groups is formed. A base station transmits a first frame requesting communication for estimating a structure of an upper network to another base station and returns a reply of a second frame to a first frame from the other base station. Then, the base station estimates a structure of the upper network and decides a structure attribute of the base station itself in the upper network on the basis of information acquired through the communications. Then, the base station notifies the other base station or a subordinate terminal of a result of the decision of the structure attribute.