To provide a wireless communication apparatus and a retransmission method realizing efficient use of a wireless resource upon receiving a retransmission request.

An HS-DSCH quality estimate section 116 estimates a channel quality of a downlink shared channel, a retransmission quality estimate unit 117 estimates required quality having been deficient in preceding packet transmission, an MCS assignment section 118 assigns a coding rate and a modulation system at which an opposite station can obtain the quality equivalent to the required quality, so that the wireless communication apparatus 100 can efficiently use a wireless resource without receiving information of deficient quality from the opposite station even in the case of a retransmission request.