A laser beam printer in which latent images are produced on a light-sensitive drum through line scanning with a laser beam modulated with print information to be printed. The laser beam is modulated with the information to be printed in such a manner that the light sensitive drum is irradiated with the laser beam except for those portions which are to be printed. The line scanning is effected with the laser beam modulated in accordance with the print information in a non-superposed manner on one hand and on the other hand with the laser beam which is modulated by information synthesized from the printing information for every two adjacent line scanning so that these two adjacent line scannings are partially covered by the line scanning based on the synthesized information.