An atomic oscillator includes an alkali-metal cell in which alkali-metal atoms are enclosed, a light source which irradiates the atoms in the alkali-metal cell with laser beams, a photodetector which detects a light amount of the laser beams passing through the alkali-metal cell to enter the photodetector, and a controller which generates sidebands including a pair of laser beams with different wavelengths by performing frequency modulation of a carrier on the light source, causes the pair of laser beams with the different wavelengths to enter the alkali-metal cell, and controls a modulation frequency according to optical absorption characteristics of the atoms by quantum interference effects of a pair of resonance laser beams, wherein the side bands include second-order or higher-order sidebands.