A magnetic sensing method comprises irradiating a pump light having a
circularly polarized component and a probe light having a linearly
polarized component onto a group of atoms contained in a cell so as to
make the lights produce an intersection region and detecting a change of
rotation angle of a plane of polarization of the probe light before and
after passing the cell. The pump light and the probe light are irradiated
in a state where a magnetic field of the direction in which the pump
light strikes the intersection region is provided with a gradient.