A clamping device for releasably holding a tool holder shank formed with a bore includes a housing having a forwardly facing surface and a bore. A drawbar is mounted reciprocally movable inside the bore and which in a forward end has engagement device, which is arranged to engage with an engagement formation inside the bore of the tool holder shank. The drawbar is, in a rear portion, formed with a drawbar aperture extending through the drawbar in a transverse direction in relation to a longitudinal axis of the same, and a cam shaft extending through the drawbar aperture and being rotatably journalled in the housing and arranged to impart an axial displacement to the drawbar in relation to the housing. The cam shaft includes first and second spaced apart cam formations and an intermediate circular cylindrical portion located between the cam formations, wherein the first and second cam formations are journalled in a first and second seating apertures, respectively, in the housing on opposite sides of the drawbar. The intermediate circular cylindrical portion is extended through the drawbar aperture, and the drawbar is insertable into the bore through the forwardly facing surface.