A tool or workpiece holder with a receiving body and a clamping device for clamping a tool or a workpiece in a receiving opening of the receiving body. The clamping device comprises a first clamping element, which can be moved in a receiving portion of the receiving body at right angles to a central axis of the receiving opening, and a second clamping element, which can be moved relative to the first clamping element at right angles to the central axis of the receiving opening by means of an actuating element. The second clamping element has conical bottom clamping surfaces on the two clamping elements for inserting the tool or workpiece into the receiving opening. An ejecting mechanism is disposed on the first clamping element for ejecting the tool or workpiece from the receiving opening when the clamping elements are moved into a disengaged position.