Information recording apparatus, information reproducing apparatus, information recording method, information reproducing method, and optical information recording medium

An information recording apparatus for recording information on a multi-layered optical information recording medium having a recording material, which changes quality according to light intensity of an irradiated light, and having an altered layer in which the recording material is already altered and a non-altered layer in which the recording material is not yet altered alternately existing in plurals is provided. The information recording apparatus includes a light source for emitting a recording light having coherency; a light path branching unit for branching a light path of the light into a first light path and a second light path; focal position control units for controlling focal positions of the light in the first and the second light path; and objective lenses for collecting the lights in the first and the second light path on the recording medium.