To provide wireless communication apparatus and system in which throughput is enhanced by suppressing the number of resending times.

Packet data decoded at a decoding section 155 is subjected to error detection at an error detecting section 156 and an ACK signal is created if an error is not detected otherwise an NACK signal is created. When an NACK signal is created and inputted to a reliability calculating section 157, the reliability calculating section 157 calculates a reliability representative of the error ratio for each block of packet data in which an error is detected, and the calculated reliability is quantized at a quantizing section 158. A transmission power control signal creating section 159 creates a signal for controlling transmission power of each block when a communication partner transmitter 100 resends the packet data in which an error is detected based on the quantized reliability. The transmission power control signal and the NACK signal thus created are transmitted to the transmitter 100.