PURPOSE: To enable to detect exactly the fringe of a photographic film, by scanning the photographic film with visible transmissive light and at the same time by scanning the same location with infrared transmissive rays.

CONSTITUTION: When a rotary shaft 4 rotates at a high speed and a cylinder 2 is moved at a low speed in the arrow 6 direction, a photographic film 1 wound around the cylinder 2 and a light shielding mask 3 are scanned with light beams from a projector 8. Light beams passing through a translucent mirror 12 enter a light receiving device 14 via a filter 13 for eliminating infrared rays, and light beams reflected on the translucent mirror impinge on a light receiving device 17. And the output of a light receiving circuit 18 is applied to a write controlling terminal W of a memory 19, and at the same time it is applied to an AND gate 20 along with the output of a rotation code generator 7, thereby allowing the output of a light receiving circuit 15 to be stored in the memory 19 via a sampling gate 21 and an AD converter 22. Thereby, it is possible to prevent the fringe of the photographic film from being sampled by error.