Provided is a synthesizer (1) including: a synthesizer unit (2) which outputs an oscillation signal based on a reference oscillation signal; a temperature detection unit (3) which detects the temperature; a time variation detection unit (4) which detects a time variation of the frequency of the reference oscillation signal in accordance with the temperature detection result obtained by the temperature detection unit; and a control unit (5) which frequency-adjusts the oscillation signal outputted from the synthesizer unit in accordance with the detection result of the time variation detection unit. The configuration enables frequency compensation control of an oscillator having a large temperature coefficient.