The present invention is generally directed to a drug delivery device for selecting and dispensing a number of user variable doses of a medicament. The device comprises a housing (10) and at least two separate component parts (40； 60), wherein for example at least one of these component parts (60) performs a movement relative to the housing (10) during dose setting and for example at least one of these component parts (40； 60) performs a movement relative to the housing (10) during dose dispensing, and wherein the relative movement of the at least two separate component parts (40； 60) with respect to each other during dose setting differs from the relative movement of the at least two separate component parts (40； 60) with respect to each other during dose dispensing. The device further comprises a monitoring device (130), wherein at least one component part (70； 120) of the device is diaphanous to allow optical detection of the movements of the at least two separate component parts (40； 60) relative to the housing (10), relative to the monitoring device (130) and/or relative to each other during dose setting and/or during dose dispensing by the monitoring device (130).
