To provide a detachable stopper for a dental drill externally fitted to and fixed on a spindle part of a dental drill. The detachable stopper for a dental drill includes a stopper main body (1) being made of an elastically deformable metal material. It has a cylindrical shape, having a slightly smaller inner diameter than an outer diameter of the spindle part in a stationary state. It further has a slit part (1a) being formed along an axial overall length from an outer peripheral face to an inner peripheral face so as to have an opening, and a diameter expanding tool insertion part (1b) bored at an axial center part of the slit part (1a). A diameter expanding tool having a shape capable of being freely inserted into and removed from the diameter expanding tool insertion part (1b) of the stopper main body (1) is inserted into the diameter expanding tool insertion part (1b) of the stopper main body (1) so as to expand the inner diameter of the stopper main body (1) to become larger than the outer diameter of the spindle part of the dental drill.
