Abstract: A dental handpiece configured to rotatably drive a dental treatment tool mounted in a chuck mechanism includes the chuck mechanism in which the dental treatment tool is mounted so as to be attachable and detachable. The chuck mechanism includes a hollow cylindrical sleeve, a cylindrical slide member, a plurality of divided movable pieces disposed in the sleeve, an elastic biasing member configured to bias the cylindrical slide member forward in an insertion direction of the dental treatment tool, and a stopper unit which restricts forward axial movement of the plurality of divided movable pieces in the insertion direction. The divided movable pieces are moved in a radial direction by relative movement between the divided movable pieces and the cylindrical slide member in the axial direction, so that fixation of the dental treatment tool and release of the fixation are performed.