A drive mechanism of an injection device for setting and dispensing of a dose of a medicament includes a body accommodating a cartridge filled with a medicament, an insert 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, a drive sleeve rotationally coupled with the piston rod and is rotationally lockable to the body for setting of a dose and rotationally releasable from the body for dispensing of a dose, respectively. 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 the insert and the drive sleeve, where the drive sleeve is rotationally released from the body when in the distal reset position.