A synthesizer includes: a synthesizer unit that outputs an oscillation signal based on a reference oscillation signal; a temperature detecting unit that detects a temperature; a time variation detecting unit that detects a time variation in frequency of the reference oscillation signal based on a result of temperature detection by the temperature detecting unit; and a control unit that adjusts a frequency of the oscillation signal outputted from the synthesizer unit based on a result of detection by the time variation detecting unit. With such a configuration, frequency compensation control is performed on a transducer having a large temperature coefficient.