A method for optically recording information on an optically re-writable information medium is described. A mark is formed on a recording medium by radiating a laser light having the strength of the short recording pulse signal followed by the off-pulse signal. The recording film is heated to form the mark and the mark is extended by thermal diffusion while the off-pulse signal is provided. Therefore, the length of the recorded mark ML is longer than the recording pulse width at a predetermined linear velocity. The erasing pulse signal follows the off-pulse signal and the extended recorded mark is erased by the erasing pulse signal. The recording method according to the present invention can form a mark on the recording medium by radiating the laser light having a shorter recording pulse width than a recording pulse width used in the conventional method to form a mark having the same length.