The present invention relates to a medicament delivery device comprising, a housing (10, 114) having a proximal and a distal end, a delivery member connected to the housing； a medicament container (84) operably arranged within the housing； a drive mechanism (102, 108) capable of acting on the medicament container (84) for priming and for expelling a dose of medicament. The invention is characterised in that the device further comprises an activator mechanism configured to interact with the drive mechanism； wherein the activator mechanism includes a rotator (82) operably arranged inside the housing (10, 114)； a safety member (128) removably arranged to the distal end of the housing and operably connected to the rotator (82)； wherein the removal of the safety member (128) causes a rotation of the rotator (82) such that the drive mechanism (102, 108) moves the medicament container (84) and a medicament container holder (56) move as a unit in the proximal direction toward the distal pointed end (44) of the injection needle (40), to first penetrate the protective sheath (48) and then a septum at the neck portion of the medicament container (84), while compressing the protective sheath (48) surrounding the distal end of the needle.
