<p>A two-wavelength semiconductor laser (1) includes: an n-type GaN substrate (101), an n-type GaAs substrate (201) arranged on a predetermined surface of the n-type GaN substrate (101); a blue-violet color laser (100) arranged on one side of the n-type GaN substrate (101) and containing a multi-quantum well active layer (105); and a red color laser (200) arranged on one side of the n-type GaAs substrate (201) and containing a multi-quantum well active layer (205). The blue-violet color laser (100) and the red color laser (200) emit laser lights having different wavelength values from each other. The blue-violet color laser (100) and the red color laser (200) are arranged in such a manner that their resonator length directions are substantially parallel and the blue-violet color laser (100) has shorter resonator length than that of the red color laser (200).</p>
