A medicament delivery device, comprising: - a housing having a proximal end and a distal end; - a hollow piston plunger being arranged within the housing; - a telescopic dose drum being concentrically arranged between the housing and the piston plunger, the telescopic dose drum being bidirectional movable in relation to the housing and in relation to the piston plunger when setting a dose and delivering a dose; - piston plunger driving means for driving the hollow piston plunger towards the proximal end, characterized in that the medicament delivery device further comprises: - a hollow drive drum sleeve being movable arranged within the hollow piston plunger and being fixedly connected to the telescopic dose drum, wherein the hollow drive drum sleeve and the hollow piston plunger are releasably coupleable to each other; - a resilient spinning element having a longitudinally rod being movable arranged within the hollow drive drum sleeve, wherein the longitudinally rod and the hollow drive drum sleeve are releasably coupleable to each other; such that after a dose is set, axial movement of the resilient spinning element towards the proximal end forces the longitudinally rod and the hollow drive drum sleeve to couple together and thereby the hollow drive drum sleeve and the hollow piston plunger also to couple together whereby the hollow piston plunger and the telescopic dose drum are displaced towards the proximal end for delivering the set dose, and such that after a set dose is delivered, axial movement of the resilient spinning element towards the distal end forces the longitudinally rod and the hollow drive drum sleeve to decouple and thereby the hollow drive drum sleeve and the hollow piston plunger also to decouple for setting a new dose, the device further comprises a stop body being connected to the hollow piston plunger such that said stop member is rotatable but not slidable in relation to said hollow piston plunger, and being also connected to the telescopic dose drum such that said stop member is slidable but not rotatable in relation to said telescopic dose drum. - a housing having a proximal end and a distal end; - a hollow piston plunger being arranged within the housing; - a telescopic dose drum being concentrically arranged between the housing and the piston plunger, the telescopic dose drum being bidirectional movable in relation to the housing and in relation to the piston plunger when setting a dose and delivering a dose; - piston plunger driving means for driving the hollow piston plunger towards the proximal end, characterized in that the medicament delivery device further comprises: - a hollow drive drum sleeve being movable arranged within the hollow piston plunger and being fixedly connected to the telescopic dose drum, wherein the hollow drive drum sleeve and the hollow piston plunger are releasably coupleable to each other; - a resilient spinning element having a longitudinally rod being movable arranged within the hollow drive drum sleeve, wherein the longitudinally rod and the hollow drive drum sleeve are releasably coupleable to each other; such that after a dose is set, axial movement of the resilient spinning element towards the proximal end forces the longitudinally rod and the hollow drive drum sleeve to couple together and thereby the hollow drive drum sleeve and the hollow piston plunger also to couple together whereby the hollow piston plunger and the telescopic dose drum are displaced towards the proximal end for delivering the set dose, and such that after a set dose is delivered, axial movement of the resilient spinning element towards the distal end forces the longitudinally rod and the hollow drive drum sleeve to decouple and thereby the hollow drive drum sleeve and the hollow piston plunger also to decouple for setting a new dose, the device further comprises a stop body being connected to the hollow piston plunger such that said stop member is rotatable but not slidable in relation to said hollow piston plunger, and being also connected to the telescopic dose drum such that said stop member is slidable but not rotatable in relation to said telescopic dose drum.