In a wireless communication system using the contention method, collisions between transmission signals sent from terminals to a base station are avoided, and a communication area is flexibly formed while suppressing unnecessary radiation of the communication area. The base station includes antennas disposed such that wireless zones cover mutually different areas, wireless units connected to the antennas in one-to-one correspondence, and for, via the respective antennas, receiving wireless signals from the terminal stations in the wireless zones and transmitting wireless signals to the terminal stations in the wireless zones, a data processing unit for processing the wireless signals received by the plurality of wireless units and generate data to be transmitted to the terminal stations, and a communication control unit for controlling the wireless units so as to, during a slot other than a transmission request slot, form one communication area combining the wireless zones of all of the antennas, and during the transmission request slot, form mutually independent communication areas less than or equal in number to the antennas.