A transmission module including a power supply voltage control unit that sets a power supply voltage to the high frequency amplifier in a variable manner, and a control circuit that controls an amplitude control unit, a phase control unit and the power supply voltage control unit. The control circuit and the power supply voltage control unit control the power supply voltage in accordance with an output power of the high frequency amplifier. The transmission module can carry out not only phase control but also amplitude control in a continuous manner, while suppressing amplitude and phase variation, and a high frequency amplifier in the transmission module is made highly efficient. In addition, a large directional gain, a low side lobe level and a low power consumption are achieved, as a phased array antenna apparatus using a transmission module.