A surgical instrument includes a handpiece to which a handpiece shaft can be flanged, and a tool mounting for receiving a tool which can be rotatably supported in the handpiece shaft for axially securing the tool in the tool mounting and for transferring a torque to the tool. The tool mounting includes a sleeve-shaped entrainment shaft with a plug-in zone for a torsion rod and torque transmission and axial locking zones for the tool. The tool mounting also includes a closure sleeve surrounding the entrainment shaft that includes a distal blocking section which acts on the axial locking zone of the entrainment shaft for axially locking and releasing the tool, and a proximal arresting section acting on the plug-in zone of the entrainment shaft for arresting the tool mounting on the torsion rod to transfer torques and axial forces and for releasing the tool mounting from the torsion rod.
