To record information as an array of optically changed portions arranged along a track in an optical storage medium, a pulsed laser beam is emitted toward the optical storage medium while causing at least one of the optical storage medium and the pulsed laser beam to be moved relative to each other. A plurality of pulses of the pulsed laser beam are emitted during a time span in which one segment of the track having a length corresponding to a length of one optically changed portion is scanned with the pulsed laser beam. An intensity of light with which a segment of the track is to be illuminated to form each individual optically changed portion is adjusted by causing a shutter to selectively reduce the number of pulses of the pulsed laser beam with which the segment of the track is to be illuminated.