In the semiconductor laser device of the present invention, a P-type diffusion region 3A is disposed in an N^- epitaxial layer 2 of a silicon submount 16, and an N-type diffusion region 4A is disposed in this P-type diffusion region 3A. The P-type diffusion region 3A and the N-type diffusion region 4A are positioned under a red laser diode 14, and the red laser diode 14 is directly connected on the N-type diffusion region 4A via electrodes 7, 8 without an insulating film. Consequently, a short circuit between the red laser diode 14 and the silicon submount 16 can be prevented. Therefore, according to this semiconductor laser device, occurrence of deterioration or failure of a semiconductor light-emitting element upon a high-temperature operation can be prevented.