Medicament delivery device comprising: - a generally elongated housing (10; 110) having opposite distal and proximal ends; - 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) comprising at least two substances, and arranged within the container holder; - a plunger rod (60; 140) comprising a proximal end arranged to act on a distal stopper arranged inside said container, and first holding means (58; 146) on its outer circumferential surface; - drive force means (64; 142) extending along a longitudinal axis of the plunger rod and being in contact with the plunger rod, capable of pushing said plunger rod for acting on said distal stopper; 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, on an inner circumferential surface, the mix member (48; 149) further comprising 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. - a generally elongated housing (10; 110) having opposite distal and proximal ends; - 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) comprising at least two substances, and arranged within the container holder; - a plunger rod (60; 140) comprising a proximal end arranged to act on a distal stopper arranged inside said container, and first holding means (58; 146) on its outer circumferential surface; - drive force means (64; 142) extending along a longitudinal axis of the plunger rod and being in contact with the plunger rod, capable of pushing said plunger rod for acting on said distal stopper; 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, on an inner circumferential surface, the mix member (48; 149) further comprising 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.