The purpose of the present invention is to provide a dental handpiece that can, on the basis of a simple and inexpensive configuration, precisely prevent fall off of a cover body due to the loosening of the screw attachment of the cover body which is screw-connected to a handpiece head part. The present invention provides a dental handpiece (1) which comprises a cartridge housing (21) that detachably holds therein a rotationally driven cutting tool (22) and that is disposed inside of an accommodation region (4) of a handpiece head part (2), wherein: a screw connection is established between a male screw thread (16) of a cover body (11) which is screwed onto the handpiece head part (2) and a female screw thread (6) of the handpiece head part (2)； a first recessed groove (15) that enables free fitting of the inner circumferential-section side of a C-ring (17), which is a ring-shaped elastic member, is provided at a male screw-thread end section provided to a peripheral wall part (12) of the cover body (11)； a second recessed groove (5) that accommodates the outer circumferential-section side of the C-ring (17) and that is disposed opposing the first recessed groove (15) when the cover body (11) is screwed onto the handpiece head part (2) is provided at a female screw-thread advancement section provided to the handpiece head part (2)； and a contact resistance force is generated by the C-ring (17) when the screw attachment of the cover body (11) becomes loose, thereby preventing the fall off of the cover body (11).La présente invention vise à fournir une pièce à main dentaire qui peut, grâce à une configuration simple et peu coûteuse, empêcher avec précision la chute d'un corps de couvercle entraînée par le desserrage de la vis la fixation du corps de couvercle qui est relié par vis à une partie de tête de pièce à main. À cet effet, la présente invention concerne une pièce à main dentaire (1) comportant un boîtier de cartouche (21) qui maintient à l'intérieur de manière
