The invention concerns an injection device for apportioning set doses of a drug from a reservoir to a subject. The injection device comprises a dose setting member (20, 70) which is screwed out from the housing (30) to set a dose and pushed axially back to the housing (30) in order to expel the set dose. A scale drum (80) is axially and inrotatable coupled to the dose setting member (20, 70) such that the scale drum (80) is rotated up a thread (34) when the dose setting member (20, 70) is rotated to set a dose. When the dose setting member (20, 70) is pushed axially back to its initial position to inject the set dose, the scale drum (80) is released from its inrotatable connection in order to allow the scale drum (80) to rotate down the thread (34) and back to its zero position.
