A medicament delivery device comprising a housing (10; 110); a medicament container holder (12; 120) rotatably locked but slidable connected to said housing, the medicament holder comprising first mix engagement means (28; 126) on its outer surface, and second linear guide means; a multi-chamber medicament container (14; 130) arranged within the container holder, a plunger rod (60; 140) comprising first holding means (58; 146) on its outer circumferential surface; drive force means (64; 142) capable of pushing said plunger rod; characterised in that said device further comprises manual mixing means (44, 148) comprising a rotatable manual knob (62,186) protruding from the distal end of the housing and a mix member (48, 149) comprising flexible holding means (52; 160) releasibly engaged to the first holding means (58; 146) for holding the plunger rod and thereby the drive force means in a pre-tensioned state and second mix engagement means (46; 150) arranged to cooperate with the first mix engagement means (28; 126) for linearly and distally displacing said container holder into the housing when said manual knob is rotated, such that the distal displacement of the container holder causes a distal displacement of the container in relation to the plunger rod, whereby the plunger rod forces the distal stopper to be proximally displaced and thereby a mixing of the components is performed.