When power to be transmitted varies, a control section instructs an AGC control section to control a gain of an IQ modulation processing section 6 in accordance with the power. A switch selects a power source voltage, corresponding to the power to be transmitted, from power source voltages V1 to V3 of a wireless module, in accordance with an instruction of the control section, so as to supply thus selected power source voltage to a power amplifier. Thus, it is possible to realize a wireless communication circuit which occupies a less area and consumes smaller amounts of power without narrowing a communication range.