A drive assembly for a drug delivery device, the drive assembly comprising: a housing having a proximal end and a distal end, a rotation member being configured to be rotated in a first direction with respect to the housing during setting of a dose of a drug and to be rotated in a second direction with respect to the housing during delivery of the dose, the second direction being opposite to the first direction, a drive component being configured to follow rotational movement of the rotation member in the second direction during delivery of the dose, a stop member being configured to prevent rotational movement of the drive component in the first direction with respect to the housing, a piston rod being configured to be displaced in the distal direction for delivering a dose of a drug and being configured such that rotational movement of the drive component in the second direction is at least partially converted into movement of the piston rod in the distal direction with respect to the housing, wherein the piston rod is a lead-screw, the drive component and the rotation member are rotatable around a common rotation axis, the drive component comprises a first drive part and a second drive part, coupled to each other such that relative rotational movement of the first and second drive parts (71, 72) is prevented and relative axial movement is permitted, the first drive part is configured for engagement with the rotation member and the second drive part is configured for engagement with the stop member, the stop member is secured against both axial and rotational movements with respect to the housing, and the stop member is configured to permit rotational movement of the drive component in the second direction with respect to the housing, characterized In that the first drive part is directly engaged with the piston rod, the rotational movement of the drive component is converted into pure linear movement of the piston rod in the distal direction along the rotation axis, the drive component comprises a biasing member for providing a force on the first and second drive parts (71, 72) for keeping at least the first drive part in abutment with the rotation member or the second drive part in abutment with the stop member, wherein the biasing member forces the first and second drive parts (71, 72) apart in opposite axial directions, wherein the drive component comprises retaining means to limit the axial separation of the first and second drive parts (71, 72), and wherein at least one of the first and second drive parts (71, 72) comprises a toothing (22, 28) for engagement with one of the rotation member and the stop member, respectively. a housing having a proximal end and a distal end, a rotation member being configured to be rotated in a first direction with respect to the housing during setting of a dose of a drug and to be rotated in a second direction with respect to the housing during delivery of the dose, the second direction being opposite to the first direction, a drive component being configured to follow rotational movement of the rotation member in the second direction during delivery of the dose, a stop member being configured to prevent rotational movement of the drive component in the first direction with respect to the housing, a piston rod being configured to be displaced in the distal direction for delivering a dose of a drug and being configured such that rotational movement of the drive component in the second direction is at least partially converted into movement of the piston rod in the distal direction with respect to the housing, wherein the piston rod is a lead-screw, the drive component and the rotation member are rotatable around a common rotation axis, the drive component comprises a first drive part and a second drive part, coupled to each other such that relative rotational movement of the first and second drive parts (71, 72) is prevented and relative axial movement is permitted, the first drive part is configured for engagement with the rotation member and the second drive part is configured for engagement with the stop member, the stop member is secured against both axial and rotational movements with respect to the housing, and the stop member is configured to permit rotational movement of the drive component in the second direction with respect to the housing, characterized In that the first drive part is directly engaged with the piston rod, the rotational movement of the drive component is converted into pure linear movement of the piston rod in the distal direction along the rotation axis, the drive component comprises a biasing member for providing a force on the first and second drive parts (71, 72) for keeping at least the first drive part in abutment with the rotation member or the second drive part in abutment with the stop member, wherein the biasing member forces the first and second drive parts (71, 72) apart in opposite axial directions, wherein the drive component comprises retaining means to limit the axial separation of the first and second drive parts (71, 72), and wherein at least one of the first and second drive parts (71, 72) comprises a toothing (22, 28) for engagement with one of the rotation member and the stop member, respectively.