A medical laser handpiece comprising a grip body, a semiconductor laser generator disposed in the grip body and an irradiation nozzle which is detachably cross-connected to the head of the grip body at an angle and includes a laser light transmitting means from the semiconductor laser generator. With this laser handpiece, an operator can accurately and easily treat even relatively small and complicated shaped teeth and periodontal sections in the mouth. In addition to a structure capable of irradiating laser lioght and a structure capable of cooling the semiconductor generator, this invention also includes a structure capable of jetting air, water and a mist of air and water, and a structure capable of reducing irradiation loss of laser light.