A wireless transmitter for infallibly delivering data to a wireless receiver, i.e., a multicast or broadcast receiver while increasing the system capacity or the individual channel accommodation capacity. A base station device (100), which is the wireless transmitter, multicasts or broadcasts data addressed to mobile station devices (150) through a common physical channel. In this device, an individual channel receiving section (103) acquires reception quality information on each wireless receiver (150), a common channel subcarrier selecting section (107) sets switchably a subchannel used for multicast or broadcast according to the acquired reception quality information out of the subchannels of the common physical channel, and a transmission power control section (110) controls the transmission power of the set subchannel.