A magnetic field measurement apparatus includes a probe beam irradiating unit that radiates a probe beam. A gas cell is arranged on an optical axis of the probe beam and shows a linear dichroism with respect to the probe beam between a first axis and a second axis. Another gas cell is arranged on the optical axis of the probe beam on the opposite side of the probe beam irradiating unit with respect to the gas cell, and shows a linear dichroism with respect to the probe beam between a third axis and a fourth axis, which are different from the first and the second axes. A measuring unit measures a difference between magnetic fields in the gas cells and on the basis of amounts of change of a plane of polarization of the probe beam that has passed through the gas cell and the gas cell.
