Drug delivery device adapted to receive a cartridge, comprising a drive tube with an inner thread, a motor assembly comprising a drive shaft and being adapted to be received inside the drive tube, a drive member attached to the drive shaft and with an outer thread in engagement with the drive tube inner thread. The drive tube is arranged axially displaceable but non-rotational relative to the motor assembly, whereby rotation of the drive member results in axial, non-rotational displacement of the drive tube. To provide flexibility the drive shaft is connected to the drive member via a first flexible joint, and the motor assembly proximal portion is connected to a support structure via a second flexible joint.
