An optical module for an atomic oscillator using a quantum interference effect includes a first light source unit that emits first resonance light, a gas cell in which an alkali metal atom is sealed, a first light detection unit that detects the intensity of the first resonance light having passed through the gas cell, a determination unit that determines whether or not the first light source unit has failed, a second light source unit that irradiates the gas cell with second resonance light when the determination unit determines that the first light source unit has failed, and a second light detection unit that detects the intensity of the second resonance light having passed through the gas cell, and the optical path length of the first resonance light in the gas cell and the optical path length of the second resonance light in the gas cell are equal to each other.