A blocking device for a shock absorber of a motor vehicle includes a first blocking member which has an insertion opening that is open-ended in a radial direction, for attachment of a piston rod of the shock absorber, and which has a receptacle. A second blocking member can be placed in a formfitting manner in the receptacle of the first blocking member in axial and radial directions to thereby close the insertion opening in the radial direction, while being held in the first blocking member.