A method of manufacturing a semiconductor laser element includes: a cleaning process of holding a semiconductor light emission element that emits light from a facet thereof in a plasma sputtering device in which a target is covered with quartz, and cleaning the facet by irradiating the facet with plasma in the plasma sputtering device; and a dielectric film formation process of transporting the cleaned semiconductor light emission element to a deposition device without exposing the semiconductor light emission element to an atmosphere, and forming a dielectric film on the cleaned facet in the deposition device.