the invention refers to an auto - injector for administering a dose of a liquid medicament , comprising : an outer casing , a syringe with a hollow needle and a stopper a torsion spring and a gear arrangement for inserting the needle , delivering the medicament , and retracting the syringe after injection . at least one skin contact trigger element is arranged at a proximal end of the outer case , the skin contact trigger element translatable in longitudinal direction between a proximal position and a distal position and biased in proximal direction in a manner to protrude from the outer casing in the proximal position , wherein in its proximal position the skin contact trigger element is arranged to prevent the spring means from being released and wherein the skin contact trigger element in its distal position is arranged to allow release of the spring means .