A semiconductor integrated circuit for communication as a component of a radio communication system of a code multiplex system such as W-CDMA is capable of transmitting a signal without distortion even in an HSDPA mode and reducing current consumption by decreasing current in an amplifier in a normal mode. An amplification circuit in a transmission system is constructed in multiple stages, and a linear amplifier whose gain changes according to operation current is used as an amplifier in each of the stages. Information of a transmission mode and information indicative of the number of channels of data multiplexed is supplied from a baseband circuit to the amplification circuit in the transmission system. The gain distribution to the amplifiers in the multiple stages is controlled so that the total gain of the amplification circuit is held constant.