A method for producing a nitride semiconductor laser light source is provided. The nitride semiconductor laser light source has a nitride semiconductor laser chip, a stem for mounting the laser chip thereon, and a cap for covering the laser chip. The laser chip is encapsulated in a sealed container composed of the stem and the cap. The method for producing this nitride semiconductor laser light source has a cleaning step of cleaning the surface of the laser chip, the stem, or the cap. In the cleaning step, the laser chip, the stem, or the cap is exposed with ozone or an excited oxygen atom, or baked by heat. The method also has, after the cleaning step, a capping step of encapsulating the laser chip in the sealed container composed of the stem and the cap. During the capping step, the cleaned surface of the laser chip, the stem, or the cap is kept clean. This method provides a long-life nitride semiconductor laser light source the light emission intensity of which is not easily reduced after a long period of use.