A hologram is recorded by irradiating, with a reference light beam, a
region corresponding to an intensity distribution of a signal light beam
on an optical recording medium. For example, the reference light beam
having the intensity distribution which substantially coincides with the
intensity distribution of the signal light beam is generated, and only
the region which substantially coincides with the region irradiated by
the signal light beam (i.e., the signal light beam defocused region) is
irradiated with the reference light beam. This enables only the necessary
region to be exposed and the regions which need not be exposed not to be
exposed. Accordingly, the hologram can be recorded without losing
information of the signal light beam and thus high-density recording can
be realized.