PURPOSE: To prevent a recording medium from making useless movement and being erroneously retrieved, by providing plural reading means, a code signal generating means, and means which detects the mounted condition of the reading means and indicating means when a reading means is not mounted.

CONSTITUTION: A mark reader 11 contains a movable substrate 21 having a port 20 and photoelectric conversion elements 25, 26, and 27, and each element 25, 26, and 27 is held at the side edge of the port 20 by means of a block 28. In front of the block 28 facing to a film moving path, a mask 29 having three apertures 291W293 is installed and each aperture of the mask 29 faces to the light receiving surface of each photoelectric conversion element 25W27. An input device 45 which inputs information for retrieval has numeral keys, through which the retrieving item of desired information to be retrieved, namely, a frame No. is inputted. A retrieval controlling circuit 46 is equipped with a counting section which counts signals outputted from an AND gate A4 and a comparing section which compares the counted value of the counting section and a frame No. inputted into the input device 45 with each other and, when both of them coincide with each other, outputs a coincidence signal.