A medicament delivery device is presented having a second housing part, a plunger rod arranged in the second housing part and configured to act on a stopper arranged inside a multi-chamber container. A first housing part contains the multi-chamber container, where the first housing part is arranged to be manually displaced into the second housing part by relative rotation between the first and the second housing parts for mixing at least two substances arranged inside the multi-chamber container. The delivery device further has a rotating contact element arranged between said plunger rod and said stopper capable of rotating in relation to said plunger rod.