A wireless transmitter of the present invention includes n (n being an integer of 2 or more) transmission antennas, a transmission circuit controller that, based on reception qualities reported from terminals, assigns a chunk to each terminal, and sends a phase-control report signal that determines whether to perform phase-control, to that chunk, and a transmission circuit unit that, to each of the n transmission antennas, performs phase-control based on the phase-control report signal, and applies a delay that obtains an optimum transmission diversity effect among a plurality of transmission diversity effects.