Medicament delivery device comprising a housing (10, 20, 24, 30), - a biased medicament delivery member guard arranged movable in relation to the housing from a proximally extended position to a retracted position, - a power pack comprising a plunger rod and a force element arranged to act on said plunger rod, which power pack is actuated by - a release clip movable in relation to the housing and arranged to said plunger rod for releasibly holding said plunger rod with the force element in a tensioned state; - a rotator rotatably arranged inside said housing, which rotator is arranged with a guide element and a medicament delivery member guard lock element (84, 86) on its outer surface, wherein said medicament delivery member guard is further arranged with a rotator activator element arranged to cooperate with said guide element for turning said rotator, upon movement of said medicament delivery member guard to the retracted position, and wherein, upon movement of said medicament delivery member guard back to the extended position, said rotator activator element will engage said medicament delivery member guard lock element (84, 86) and lock said medicament delivery member guard in a shielding position after removal of said medicament delivery device from a medicament delivery site, characterised in that said medicament delivery member guard is arranged with release clip activation elements operably arranged to act on said release clip for releasing said plunger rod, wherein said release clip activation elements comprise distally directed tongues arranged to act on activation surfaces on said release clip; wherein said release clip is arranged turnable inside the housing, that said activation surfaces comprise inclined surfaces such that interaction between said tongues and said inclined surfaces causes a turning of said release clip from a blocking position to a release position; and wherein said release clip comprises a central passage through which the plunger rod may pass, inwardly directed ledges in said passage arranged to cooperate with circumferentially directed cut-outs (92, 94) in said plunger rod for releasibly holding said plunger rod. - a biased medicament delivery member guard arranged movable in relation to the housing from a proximally extended position to a retracted position, - a power pack comprising a plunger rod and a force element arranged to act on said plunger rod, which power pack is actuated by - a release clip movable in relation to the housing and arranged to said plunger rod for releasibly holding said plunger rod with the force element in a tensioned state; - a rotator rotatably arranged inside said housing, which rotator is arranged with a guide element and a medicament delivery member guard lock element (84, 86) on its outer surface, wherein said medicament delivery member guard is further arranged with a rotator activator element arranged to cooperate with said guide element for turning said rotator, upon movement of said medicament delivery member guard to the retracted position, and wherein, upon movement of said medicament delivery member guard back to the extended position, said rotator activator element will engage said medicament delivery member guard lock element (84, 86) and lock said medicament delivery member guard in a shielding position after removal of said medicament delivery device from a medicament delivery site,