A medicament delivery device has an elongated housing; a medicament container carrier for a medicament container to which a medicament delivery member is attached, the carrier being slidable in the housing; a trigger unit; a cover unit coaxial and slidable in the housing; a release mechanism adapted to be actuated partly by the trigger unit and partly by movement of the cover unit; a preloaded drive unit releasably connected to the carrier and controlled by the release mechanism for advancing the carrier to a predetermined proximal position in relation to the housing at which the drive unit becomes disconnected from the carrier for advancing a slidable stopper in the container and thereby dispensing the medicament; and a braking mechanism acting between the preloaded drive unit and the release mechanism for controlling the speed of the preloaded drive unit when advancing the slidable stopper in the container.