A Medicament delivery device comprises: a tubular housing having a proximal end and an opposite distal end； an injection drive configured to exert force on a medicament container to expel medicament； and an injection drive holder configured to releasably hold the injection drive in a pre-tensioned state before injection of the medicament. The injection drive holder comprises a tubular extension part for receiving the injection drive to be axially movable therein and a release ring coaxially arranged on the tubular extension part, the release ring being axially movable between proximal and distal positions along the outer surface of the tubular extension part. The tubular extension part is configured to engage with the injection drive when the release ring is at the proximal position and release the injection drive as the release ring moves distally leaving the proximal position.
