An optical module for an atomic oscillator using a quantum interference effect includes a light source adapted to emit light including a fundamental wave having a predetermined wavelength, and sideband waves of the fundamental wave, a wavelength selection section receiving the light from the light source, and adapted to transmit the sideband waves, a gas cell encapsulating an alkali metal gas and irradiated with light transmitted through the wavelength selection section, and a light detection section adapted to detect an intensity of light transmitted through the gas cell, and the wavelength selection section including an optical filter section adapted to transmit light having a wavelength within a predetermined wavelength range, and an optical filter characteristic control section adapted to vary the wavelength range of light to be transmitted by the optical filter section.