A semiconductor laser device is provided with a semiconductor layer including an active layer and a plurality of cladding layers sandwiching the active layer. The active layer includes a stripe-shaped active region, a pair of first refractive index regions and a pair of second refractive index regions sandwiching the active layer and the pair of first refractive index regions. When λ is the laser oscillation wavelength, na is the effective refractive index of the active region, nc is the effective refractive index of the first refractive index regions, nt is the effective refractive index of the second refractive index regions, w is the width of the active region, and m is a positive integer, the semiconductor laser device satisfies na>nt>nc, and the conditions of equations (5), (8) and (9).