A circuit device includes an oscillation circuit which is electrically coupled to a first node to electrically be coupled to one end of a resonator and a second node to electrically be coupled to another end of the resonator, and is configured to oscillate the resonator to generate an oscillation signal, and a waveform shaping circuit which is coupled to the first node, to which the oscillation signal is input from the first node, and which is configured to output a clock signal obtained by performing waveform shaping on the oscillation signal, and a duty adjustment circuit configured to supply the first node with a bias voltage which is variably adjusted based on adjustment data to thereby adjust a duty ratio of the clock signal.