Disclosed is a wireless communication system capable of avoiding interference even when a network including a secondary user coexists. The wireless communication system includes a primary user belonging to a first network, a first secondary user belonging to a second network, and a coexistence manager (CM). The coexistence manager (CM) acquires information relating to spectrum holes that are, at least temporarily, not in use by the primary user. In addition, the coexistence manager (CM) determines whether or not usage of the spectrum holes by the first secondary user causes interference. If the determination result is that interference is caused, coexistence manager (CM) notifies to this effect a second secondary user belonging to a third network, which differs from the second network.