Where two or more wireless communication networks having mutually different physical layers coexist, and wireless communication is performed between a plurality of devices and a coordinator in each one of the wireless communication networks, the coordinator of one wireless communication network generates coexistence notification frame data to notify coordinators of the other wireless communication networks of existence of the coordinator. This first coordinator encodes the generated coexistence notification frame data, inserts source data so as to be set as FEC data, modulates the FEC data through a Gaussian frequency shifting keying system (GFSK) so as to be set as a GFSK modulated wave signal, and transmits the GFSK modulated wave signal to the coordinators of the other wireless communication networks.