A voltage sensor includes a vibrator configured to be supported by a mechanical supporting portion and to be given a floating potential, a drive electrode configured to be disposed adjacent to the vibrator and to resonate the vibrator with applied AC voltage, a driver configured to apply an AC voltage that crosses 0 V to the drive electrode, a fixed electrode configured to be disposed adjacent to the vibrator with a gap formed between the fixed electrode and the vibrator, and a calculator configured to detect a magnitude of a measurement target voltage based on a change of a resonant frequency of the vibrator when the measurement target voltage is applied to the fixed electrode.