The present invention relates to a medicament delivery device having a longitudinal axis and a transversal axis, wherein the device comprises a proximal and a distal housing part connected to each other and extending along the longitudinal axis, wherein the proximal housing part is arranged to accommodate a medicament container a drive member rotatable arranged inside the distal housing part and comprising a first circumferentially extending set of interacting means a threaded plunger rod extending along the longitudinal axis, being rotationally locked through a central passage of the distal housing part and arranged to act on a stopper inside said medicament container a threaded drive nut threadedly connected to said plunger roda turnable dose setting member coaxially arranged around the drive member and rotatably connected to the distal housing part a torsion spring having a first end connected to the turnable dose setting member and a second end connected to a central hub oft he drive memberwherein the hub the torsion spring the turnable dose setting member and the drive member are coaxially arranged about the transversal axis which is generally perpendicular to the longitudinal axis, and in that said threaded drive nut 36 is arranged with second interacting means on its outer surface cooperating with the first circumferentially extending set of interacting means such that when said drive member is forced to rotate by said torsion spring, the drive nut is also rotated whereby the plunger rod is moved in the proximal direction for expelling a dose of medicament.
