To provide an oscillator having superior noise characteristics.

The oscillator is provided with an oscillation circuit and a buffer circuit, that uses the oscillation signals of the oscillation circuit as the input signals. The buffer circuit is provided with a push-pull amplifier circuit having two base-grounded transistors. As a result, the input impedance of the buffer circuit is reduced, and distortion in the waveform of input signals is suppressed. This renders the oscillator superior in noise characteristics.