A medical or dental handpiece which has an outer sleeve, a tool-holding sleeve for holding a treatment tool, wherein the tool-holding sleeve has a central axis about which the tool-holding sleeve can be rotated and wherein the tool-holding sleeve can be induced to a stroke motion by a driveshaft of the handpiece, and an adjusting device, which is designed to secure the tool-holding sleeve selectively in a rotational position or to allow a free rotatability of the tool-holding sleeve, wherein the adjusting device has a fixation element, which secures or releases the tool-holding sleeve and at least one adjusting element, which is at least operatively connected to the fixation element, wherein the adjusting element is movable substantially in parallel with the central axis of the tool-holding sleeve.
