A drive mechanism for a medication delivery device, comprising: - a housing (13, 17, 40) having a proximal end and a distal end, - a rotation member which is adapted to be rotated in a first direction with respect to the housing during setting of a dose of a medication and to be rotated in a second direction with respect to the housing during delivery of the dose, the second direction being opposite to the first direction, - a piston rod which is adapted to be displaced in a distal direction with respect to the housing for delivering the dose, - a drive member which is adapted to follow rotational movement of the rotation member in the second direction during delivery of the dose, wherein the drive member and the rotation member are rotatable about a common rotation axis, and - a stop member which is permanently secured against rotational movement with respect to the housing (13, 17, 40) and is coupled to the drive member by an uni-directional clutch mechanism adapted to prevent rotational movement of the drive member with respect to the housing in the first direction during setting of the dose, wherein the rotational movement of the drive member in the second direction is converted into movement of the piston rod in the distal direction with respect to the housing, wherein the drive member is coupled to the piston rod so as to convert its rotational movement in the second direction into distal movement of the piston rod with respect to the housing (13, 17, 40), wherein the piston rod is displaced in the distal direction with respect to the housing (13, 17, 40) along the rotation axis, wherein the drive member abuts the rotation member during movement of the rotation member for setting and delivery of the dose, and wherein the drive member comprises a toothing provided at a proximal end of the drive member and the rotation member comprises a toothing, wherein the toothing of the drive member and the toothing of the rotation member face one another and are configured to mate with one another, characterized in that a resilient member is arranged on the distal end side of the stop member which provides a force on the stop member which is displaceable with respect to the housing such that the drive member permanently abuts and/or engages both of the stop member and the rotation member during rotational movement of the rotation member for setting and delivery of the dose, that the drive member, the stop member and the rotation member are formed as a respective sleeve, with the drive member being arranged between the stop member and the rotation member, and that the rotation member is provided with an outer thread. - a housing (13, 17, 40) having a proximal end and a distal end, - a rotation member which is adapted to be rotated in a first direction with respect to the housing during setting of a dose of a medication and to be rotated in a second direction with respect to the housing during delivery of the dose, the second direction being opposite to the first direction, - a piston rod which is adapted to be displaced in a distal direction with respect to the housing for delivering the dose, - a drive member which is adapted to follow rotational movement of the rotation member in the second direction during delivery of the dose, wherein the drive member and the rotation member are rotatable about a common rotation axis, and - a stop member which is permanently secured against rotational movement with respect to the housing (13, 17, 40) and is coupled to the drive member by an uni-directional clutch mechanism adapted to prevent rotational movement of the drive member with respect to the housing in the first direction during setting of the dose,