PURPOSE: To reduce the number of parts and to simplify an assembly process by eliminating the need for an optical waveguide between each light emitting part and a photosensitive part for a monitor, which was necessary for a conventional multibeam laser device.

CONSTITUTION: Semiconductor laser pellets 3a, 3b are mounted on a heat sink 2 on a package 1. Photosensitive element pellets 5a, 5b for monitor are arranged behind each laser pellet. A multilayer thin film interference filter is provided to a surface of the photosensitive element pellets 5a, 5b, respectively. Since the multilayer thin film interference filter has incidence angle selectivity, it is possible to receive projection light alone of a laser pellet corresponding to each photosensitive element by providing the filter without using an optical waveguide.