The present invention relates to a drive mechanism of a drug delivery device for dispensing of a dose of a medicament, the mechanism comprising: an elongated housing (20) extending in an axial direction (1, 2), a piston rod (160) to operably engage with a piston (14) of a cartridge (12) to displace the piston (14) in axial distal direction (1), a dose setting member (120; 220) rotatably arranged at a proximal end of the housing (20) for setting of a dose, a base member (60; 260) having a proximally extending shaft portion (61; 261) at least partially enclosed by the dose setting member (120; 220), a last dose limiting member (140; 240) radially disposed between the dose setting member (120; 220) and the base member (60; 260) and having at least one radial stop (143; 243a, 243b) to limit a rotational displacement of the dose setting member (120; 220) relative to the base member (60; 260), wherein the last dose limiting member (140; 240) is rotatably locked but axially displaceable to one of the base member (60; 260) and the dose setting member (120; 220) and wherein the last dose limiting member (140; 240) is threadedly engaged with the other one of the base member (60; 260) and the dose setting member (120; 220).