The drive mechanism for a drug delivery device comprises a piston rod, which is displaced in a distal direction for a delivery of a dose and in a proximal direction for a reset, and a resilient member, which acts on the piston rod during a reset and tends to restrict the movement of the piston rod in the proximal direction. The resilient member may be a biasing member provided for an automatic reset, a compression spring entering the piston rod or a torsion spring provided to generate a rotation. The drug delivery device is provided with such a drive mechanism.