DETECTING METHOD OF FOLDING AMOUNT OF CONTINUOUS FORM

PROBLEM TO BE SOLVED: To provide a detecting method of accurately detecting a distance from a swing fin to a continuous form stacked on a stacker table in a paper folding part of an electronically photographing device. SOLUTION: A folding method part comprises the swing fin for folding the continuous form with an oscillating operation while feeding paper, the stacker table for stacking the continuous form folded by the swing fin, and an optical distance sensor for detecting a distance to a facing matter. The detecting direction of the optical distance sensor is determined vertically from the swing fin side toward the stacked continuous form, timing of the oscillating operation of the swing fin is adjusted not to block an optical path of the optical distance sensor, and a distance to the stacked continuous form is detected.