A transmission circuit broadens a controlled bandwidth of a voltage controller while ensuring voltage withstanding ability of the voltage controller. The transmission circuit includes a phase modulator outputting a phase modulation signal and a power amplifier including a transistor. The transmission circuit also includes a collector controller controlling a collector voltage, a base controller controlling a base bias voltage, and a switching controller, which switches, when a level indicated by the power level signal is lower than a predefined value, to control the collector controller in accordance with an amplitude signal and a power level signal, and which switches, when the level indicated by the power level signal is equal to or more than the predefined value, to control the base controller in accordance with the amplitude signal and the power level signal.