PURPOSE: To provide a method for automatic reversing wherein a defect existing on a running continuous printing film is detected and even if the continuous printing film is wound up due to inertia after the detection, this wound printed film is unwound automatically to a required position.

CONSTITUTION: A method for unwinding with a constitution wherein a feeding reel and a winding reel are provided on a machine and a plurality of guide rollers are provided between these both reels and a detector, a marking device, a detecting table and a detecting tube detecting a marking are provided by facing them to the continuous printing film running along the guide rollers from the feeding reel; in addition, on the feeding side, a reversely driven pulse motor connected with the detecting tube and a rotary encoder are provided to detect a defect position; then, a marking is made by this signal and the mark on the printing film running by an inertia force and the pulse motor wherein the number of pulses are set this signal and the rotary encoder are worked and film is unwound automatically to a required position by comparing the pulses of the pulse motor and the encoder.