To make a device simple and inexpensive by reducing the number of parts.

By a detection means 54, a voltage signal from a perforation sensor 13 is periodically sampled in the midst of a film feeding action. That means, the voltage signal is fetched at several (msec) intervals through an A/D conversion means 53. By using data stored in a this-time storage part 41, a last-time storage part 42 and a time-before-last storage part 43, it is detected whether the voltage signal of the sensor 13 tends to increase or decrease and the detected result thereof is stored in a change state storage part 45. Besides, it is detected whether inversion exists or not between the increasing tendency and the decreasing tendency. When the inversion is detected by the detection means 54, the number of inverting time is stored in a storage part for storing the number of inverting time 44 by a counter 55. When the number of stored time becomes 16, it is decided that one frame of a film 21 is fed.