A laser diode module has a laser diode, a lens for condensing the laser beam from the laser diode, an optical fiber for receiving the laser beam from the lens at the end face thereof, and support assembly for supporting the laser diode, the lens, and optical fiber, the support assembly positions the end face of the optical fiber at a deviation position apart from the focal point of the lens by an allowable distance when a temperature of the laser diode module is room temperature and moves the end face of the optical fiber at a close position relatively closer to the focal point than the deviation position when the temperature of the laser diode module rises from the room temperature.