The present invention provides a high frequency power amplifier circuit capable of obtaining sufficient detection output even in a range where a request output power level is low and performing a desired output power control by a control loop with the detection output in a radio communication system which detects output power and performs feedback control. An output power detection circuit which detects the level of output power on the basis of an AC signal supplied from a final amplification stage of a high frequency power amplification circuit via a capacitive element has a circuit configuration such that in a state where the output power control voltage is lower than a certain level, current (Isu) according to the output power control voltage is generated and supplied to the output power detection circuit, and detection sensitivity of the output power detection circuit improves according to the current.