The present invention relates to a medicament delivery device comprising a tubular housing arranged to accommodate a medicament container; a dose setting member being rotatable in relation to the housing for setting a dose to be expelled; a plunger rod arranged to act on a stopper inside said medicament container such that a translational movement of the plunger rod in a proximal direction causes the dose to be expelled; a drive means for converting a rotational movement of the dose setting member into translational movement of the plunger rod; a clock spring arranged transversal in relation to the longitudinal direction of the device and having a first end connected to the dose setting member and a second end connected to a drive member which is interactively connected to the plunger rod, such that the clock spring is tensioned upon rotation of the dose setting member; and a hold and release member releasably connected to the drive member for holding and -releasing the clock spring in-from a tensioned state; wherein the device further comprises activation means having a distal end protruding through a distal passage of the dose setting member, and being interactively connected to the hold and release member such that when said activation means is pushed in the proximal direction, the hold and release member is proximally moved whereby the clock spring is released from its tensioned state forcing said drive member to rotate.