Transmission destination determiner 301 selects communication terminals to be candidates to transmit a packet to from a packet transmission control signal, and determines a transmission destination apparatus based on CQI signals from the communication terminal apparatuses selected. Packet channel quality estimator estimates the quality of a received packet at the transmission destination apparatus based on the CQI signal, and, based on the estimation result, calculates a request packet quality for achieving a target packet quality upon retransmission based on the estimation result. Transmission power determiner 304, when receiving an ACK signal from the transmission destination apparatus, sets transmission power at a predetermined level, and, when receiving a NACK signal, determines transmission power to fulfill the request packet quality. By this means, the base station apparatus is able to estimate receiving quality of a packet at the communication terminal apparatus without having the communication terminal apparatus transmit packet quality information and determine transmission power required for retransmission based on the receiving quality of the packet.