DENTAL HAND PIECE

PROBLEM TO BE SOLVED: To allow spray injection for cooling the cutting part to be performed effectively. SOLUTION: A dental hand piece is provided with an outer casing 20 for a cartridge insertible freely attachably and detachably inside the head housing 10 at its tip end, and a chuck mechanism 30 mounted freely rotatably inside the outer casing 20 for the cartridge. Dental treatment is performed with a bar (blade) 50 attached to the chuck mechanism 30. At the tip end on the bar- attaching side of the outer casing 20, an annular passage 23 for aeration and an annular passage 24 for washing are separately provided in the axial direction. Also on the side of the outer casing 20, an aeration hole 21 communicating with the annular passage 23 is provided, as is a hole for washing communicating with the annular passage 24. A plurality of passages 29 are provided, at spaces apart in the circumferential direction, which are opened at the end face of the outer casing 20 and also extended in the axial direction so as to communicate with the annular passage 23 for aeration, and the each passage also communicating with the annular passage 24 for washing through a passage 61.