A WiMAX compatible base station (BS) includes: an allocator unit (10B, 10C) configured to allocate allocation information of the downlink burst (DL-MAP) as transmission information in a first region (MAP region), and to allocate the downlink burst as transmission information in the second region (downlink burst region); and a transmitter unit (10F) configured to transmit the allocation information of the downlink burst with a non-directional beam, and to transmit the downlink burst with a non-directional beam or a directional beam. When detecting an unused region (A) where no transmission information is allocated after allocating the transmission information in the first region and the second region in the frame structure, the allocator unit is configured to reallocate, by use of the detected unused region, the allocation information of the downlink burst as the transmission information in the first region.