An atomic magnetometer, which operates in a communication system using a magnetic signal in a very low frequency (VLF) band, may comprise: a vapor cell comprising one or more alkaline metal atoms; a pump light source configured to provide circularly polarized pump beams to the vapor cell; an irradiation light source configured to provide linearly polarized irradiation beams to the vapor cell; a magnetic signal detecting unit configured to detect a magnetic signal by measuring a polarization rotation angle from the linearly polarized irradiation beam passing through the vapor cell; and a bias magnetic field control unit configured to control a bias magnetic field applied to the vapor cell.