A dental handpiece having a grip with a head in which a treatment tool may be detachably attached. A front casing portion of the grip is continuous to a rear casing portion at an obtuse angle. A first rotary shaft is rotatably supported in the rear casing portion. A cylindrical jacket extends from the head and is arranged in the front casing portion toward the first rotary shaft. A second rotary shaft is rotatably supported in the jacket, and is operatively connected to the treatment tool at one end and to the first rotary shaft at the other end via a gear. The rotary shafts transmit driving force to the head section to drive the treatment tool. The jacket is provided with an engagement groove on its circumferential surface. An engaging device disposed in the rear casing portion detachably engages the groove, thereby fixing the jacket in the front casing portion.