The present invention relates to a medicament delivery device comprising an elongated housing arranged to contain a medicament container which medicament container contains a number of doses；a dose counter mechanism comprising a dose drum arranged with dose indicia on its outer surface and visible through a window on said housing；a rotatable driver connected to said dose drum；a plunger rod arranged to act on said medicament container for expelling a dose of medicament；an actuation mechanism connected to said rotatable driver and to said plunger rod when said medicament delivery device is actuated； wherein said dose drum is arranged with internal threads, in engagement with corresponding threads on said driver, wherein said threads have a certain pitch； wherein said dose drum is also arranged with external threads in engagement with corresponding threads arranged fixed in relation to said housing,wherein said threads have a certain pitch；and wherein the pitch of the threads between the dose drum and fixed in relation to the housing is lesser than the threads between the dose drum and the driver such that when said driver is rotated a certain angular distance, said dose drum is rotated a lesser angular distance.
