A medicament delivery device is provided having a power body having opposite proximal and distal ends, a plunger rod driver coaxial and movably arranged in relation to said power body, a plunger rod coaxial and movably arranged in relation to said plunger rod driver, a force spring element operably connected between the plunger rod and the power body The plunger rod driver has a first holding elements arranged to interact with second holding elements on the plunger rod and with the power body for releasably holding the plunger rod with the force spring element in an injection tensioned state.
