An atomic oscillator includes: a light emitting element; a temperature control element that controls a temperature of the light emitting element; an atomic cell which is irradiated with a light from the light emitting element and in which an alkali metal atom is contained; a light detection element that detects a light transmitted through the atomic cell; an oscillator that outputs an oscillation signal; a wave detection circuit that detects a wave of a signal, which is based on an output of the light detection element, using the oscillation signal of the oscillator, and outputs a wave detection signal; and a drive circuit that includes a constant current circuit generating a current of a specified value for driving the light emitting element and superimposes a modulation current, which is based on the oscillation signal of the oscillator, on the current to output a drive current to the light emitting element.