A clamping or chucking apparatus for a shaper cutter for a gear shaping machine, especially a generating shaping machine for fabricating gears, containing an axially to-and-fro movable ram spindle and a shaper cutter holder affixed at one end of the ram spindle and having a contact surface for the shaper cutter. A centering projection protrudes axially away from the contact surface and serves for mounting the shaper cutter. A clamping plate is attached at the end of the centering projection over a clamping mandrel or plug. The coaction of the clamping plate and clamping mandrel serves to clamp the shaper cutter against the contact surface of the shaper cutter holder. The ram spindle is hollow and contains a spring arrangement and a piston. The spring arrangement is prestressed in order to exert an axial clamping force and is operatively connected by a coupling with the shaper cutter holder or shaper cutter. The coupling is constructed to transmit the clamping force and can be easily released after elimination of such clamping force. The piston limits within the ram spindle a cylinder chamber which can be connected to a pressurized medium source and eliminates the clamping force of the spring arrangement when the cylinder chamber is pressurized.