A plurality of types of recording pulse control rules for which the
recording pulse waveform is determined according to the information
signals to be recorded are stored in advance in an optical disk. When
recording to the optical disk, information is recorded using a recording
pulse where, due to the focused laser beam, the temperature in the
recording layer cools more rapidly at a second information recording
layer closer to the side where light is incident than at a first
information recording layer farther away from the side where light is
incident.