The invention relates to a medicament delivery device comprising a housing having a proximal and a distal section formed by a first housing part and a second housing part a first compartment formed inside said proximal housing section for ac commodating a medicament container with at least one stopper, a circle-segment-formed second compartment formed inside said distal housing section for accommodating a drive unit capable of moving said at least one stopper in the proximal direction. The drive unit comprises a support wheel rotatably arranged inside said second compartment, comprising a central tubular hub on which a first and a second washer- formed parallel disks are fixedly attached, and interconnected by an abutment cross-wall spherical members arranged in a row between the abutment wall and adjacent said stopper, and guided in a channel formed by the inner periphery of the circle-segment-formed second compartment, by the outer periphery of said central tubular hub, by the inner side surfaces of the washer-formed disks and by a guide member a clock spring coaxially arranged within said central tubular hub having an outer end connected to said central tubular hub and an inner end connected to a one direction-rotatable tubular hub coaxially arranged around a shaft fixedly attached to the first housing part and an activation member interactively connected to said first washer-formed disk by co-acting hold- and-release means such that when said activation member is in a non-depressed position said support wheel and said clock spring are held in at least one tensioned and FIG.1A
