Disclosed is a digital signal processing portion that amplifies a high frequency signal resulting from digitally modulating data to be transmitted. An envelope detection portion (DETenv) generates the high frequency signal's envelope voltage. A comparator compares this envelope voltage with reference voltage Vref to generate two-state output. According to this two-state output, a power converter circuit converts power supply voltage Vbatt into power and outputs power supply voltage Vpa for a power amplifier. While the envelope voltage is larger than the reference voltage Vref, for example, the power supply voltage Vpa is changed from voltage V1 to V2 (larger than V1). In this manner, there are provided a high frequency power amplifier and a transmitter capable of decreasing distortion of transmission signals by means of a relatively simple technique.