The invention relates to an injection device, comprising a generally elongated tubular housing having opposite proximal and distal ends； a needle shield sleeve slidably and coaxially arranged inside the housing and protruding a distance outside the proximal end of the housing； a syringe carrier mechanism comprising a syringe carrier slidably and coaxially arranged to the needle shield sleeve, wherein said syringe carrier comprises a syringe having a medicament and a needle； a first activator member (110) slidably and coaxially arranged to the housing and connected to said needle shield sleeve； an actuating member (80) slidaby and coaxially arranged to the first activator member； a drive mechanism slidably and coaxially arranged to the actuating member and to the syringe carrier mechanism, said drive mechanism being controlled by the actuating member, said drive mechanism comprising a plunger rod (60) arranged to act on the syringe a first compression spring arranged to drive the plunger； a second activator member (102) slidably and coaxially arranged to the distal end of the housing； wherein the first and the second activator members are coaxially movable relative each other to an activation position wherein the activator members are co-acting independent of the sequence in which said activator members are activated； and wherein only in the activation position is the actuating member capable of releasing the drive mechanism to move said syringe carrier mechanism for penetrating the needle and to deliver said medicament though the needle.
