In a gyro sensor, a TDC detects a magnitude of vibration of a vibrator. A drive circuit (excluding the TDC) determines a duty ratio of a PWM drive signal in accordance with the magnitude of vibration so that the magnitude of vibration becomes a predetermined magnitude and outputs the PWM drive signal having the determined duty ratio. The drive circuit (excluding the TDC) includes a control circuit and a DCO. The control circuit measures time corresponding to the control value by using a gate delay time, generates the PWM drive signal having a pulse width corresponding to the control value and outputs the PWM drive signal.