PURPOSE: To provide a head positioning mechanism wherein a carrier can be restored to an original printing gap state even if said carrier is retracted in order to set paper by providing a special adjusting lever to the shaft support part of a crank shaped guide shaft advancing and retracting the carrier toward a platen.

CONSTITUTION: A worm gear 71 is mounted to the peripheral flange part of a wheel 70 and a pin 72 is provided to the inside thereof to concentrically fix said gear to the eccentric shaft 16a of a crank shaped guide shaft advancing and retracting a carrier. The worm gear 71 provided to the side of the wheel 70 and the worm gear 41 provided to the side of an adjusting lever 40 are arranged at a position threading both gears and the pin 72 is provided to a position coincided with the guide orifice 31 provided to the side of a set lever 30 in a freely slidable manner. When the adjusting lever 40 is rotated, the wheel 70 is rotated through the worm gear 71 and the eccentric shaft 16a is rotated to make it possible to alter the gap of a platen and a head. When a reset lever 50 is revolved for replacing paper, the engagement of a notch 65a and a pawl 50a is released and a rotary plate 60 is rotated to enlarge the gap. The carrier is restored by revolving the set lever 30.