In a semiconductor laser device, a flange (33) of a cap (32) is provided with straight-line cut-off portions (34) that are the same in number as notches (36, 37) of a stem (35). With the cut-off portions (34) positioned so as not to overlap the notches (36, 37) of the stem (35) in position, welding between the cap (32) and the stem (35) is performed. The cut-off portions (34) of the cap (32) secure obtainment of a reference plane 38 with a large area in a place where the notches (36, 37) of the stem (35) are absent. As a result, sufficient precision in optical characteristics can be secured while suppressing an influence of unevenness of the stem (35) having a small diameter on a deviation angle of an optical axis from a normal line to a reference plane of an optical pickup.