A semiconductor laser device includes a semiconductor laser for emitting a laser beam, a coupling lens for collimating the laser beam as passing therethrough and a supporting member for supporting the laser and the coupling lens. As the ambient temperature changes, the supporting member either expands or contracts, thereby varying the distance between the laser and the coupling lens. However, it is so structured that the focal distance of the coupling lens varies in accordance with a change in the wavelength of the laser beam emitted from the laser which is caused by the change in the ambient temperature, so that the change in the distance between the laser and the coupling lens is effectively cancelled by the change in the focal distance of the coupling lens, whereby the laser beam passing through the coupling lens remains collimated even if the ambient temperature changes.