A chuck mechanism for a dental handpiece holds a columnar rotary tool for dental care rotatably with an annular rotor of the dental handpiece. The columnar rotor tool is concentrically detachable to the annular rotor which is rotatably attached to a head part of the dental handpiece. The chuck mechanism has an annular chucking member with a cylindrical base part into which the annular rotor is integrally fitted and an elastic chucking piece having a chucking pawl for engaging with a locking groove formed at a base end of the rotary tool. The chuck mechanism enables the rotary tool to be easily removed from the annular rotor by elastically deforming the elastic chucking piece against elastic force of the elastic chucking piece to disengage the chucking pawl from the locking groove.