A drive mechanism of an injection device for setting and dispensing of a dose of a medicament, the drive mechanism comprising: - a body extending in an axial direction to accommodate a cartridge filled with the medicament, or a body connectable with a cartridge holder to accommodate the cartridge, - an insert rotationally fixed to the body and axially displaceable inside the body between a proximal operating position and a distal reset position, - a piston rod to operably engage with a piston of the cartridge, wherein the piston rod extends in axial direction and is threadedly engaged with the insert, - a drive sleeve rotationally coupled with the piston rod and extending in axial direction, wherein the drive sleeve is rotationally lockable to the body for setting of a dose and wherein the drive sleeve is rotationally releasable from the body for dispensing of a dose, respectively, - wherein the drive sleeve is axially displaceable relative to the body from a proximal operating position into a distal reset position through an axial connection of insert and drive sleeve, wherein the drive sleeve is rotationally released from the body when in distal reset position, characterized by - a lock member radially arranged between the drive sleeve and the body and being rotationally locked to the body, wherein the lock member is axially displaceable relative to the body between a proximal dose setting position and a distal dose dispensing position and wherein the lock member is axially slidably disposed inside the body to selectively engage or to disengage with the drive sleeve, wherein when the lock member and the drive sleeve are mutually engaged the drive sleeve is rotationally locked to the body via the lock member, - wherein the lock member is axially displaceable relative to the body in distal direction against the action of a dispensing spring, wherein a distal end of the dispensing spring is supported by or is connected with the insert and wherein a proximal end of the dispensing spring is supported by or is connected with the lock member and - wherein the insert is axially slidably arranged inside the body in proximal direction against the action of a reset spring. - a body extending in an axial direction to accommodate a cartridge filled with the medicament, or a body connectable with a cartridge holder to accommodate the cartridge, - an insert rotationally fixed to the body and axially displaceable inside the body between a proximal operating position and a distal reset position, - a piston rod to operably engage with a piston of the cartridge, wherein the piston rod extends in axial direction and is threadedly engaged with the insert, - a drive sleeve rotationally coupled with the piston rod and extending in axial direction, wherein the drive sleeve is rotationally lockable to the body for setting of a dose and wherein the drive sleeve is rotationally releasable from the body for dispensing of a dose, respectively, - wherein the drive sleeve is axially displaceable relative to the body from a proximal operating position into a distal reset position through an axial connection of insert and drive sleeve, wherein the drive sleeve is rotationally released from the body when in distal reset position, characterized by - a lock member radially arranged between the drive sleeve and the body and being rotationally locked to the body, wherein the lock member is axially displaceable relative to the body between a proximal dose setting position and a distal dose dispensing position and wherein the lock member is axially slidably disposed inside the body to selectively engage or to disengage with the drive sleeve, wherein when the lock member and the drive sleeve are mutually engaged the drive sleeve is rotationally locked to the body via the lock member, - wherein the lock member is axially displaceable relative to the body in distal direction against the action of a dispensing spring, wherein a distal end of the dispensing spring is supported by or is connected with the insert and wherein a proximal end of the dispensing spring is supported by or is connected with the lock member and - wherein the insert is axially slidably arranged inside the body in proximal direction against the action of a reset spring.