In a communication where a retransmission is attained based on a Hybrid-ARQ (Automatic repeat ReQuest) system, retransmission having no gain is reduced, and improvement of the transmission efficiency is intended. A mode determining unit 111 of a base station carries out calculation to obtain a received signal quality difference information indicative of a difference between a received signal quality at the current stage and that of a past stage at a terminal, and supplies to a control unit 112. The control unit 112 controls a power setting unit 113 based on the received signal quality difference information supplied from the mode determining unit 111, and thus a transmission power of a signal transmitted from an adaptive coding and modulation unit 13 can be controlled. The present invention can be applied to a base station of a portable telephone communication network, for example.