To efficiently and accurately perform setting of a threshold value to a comparator for processing a received light signal outputted from a sensor in the film moving amount detector of a camera.

When a film with perforations along frames is rolled up in frame units, the film moving amount detector of a camera projects light onto the moving area of perforations and receives the reflected light or transmitted light, and detects the film moving amount by counting the perforations from the variations of the received light signal. The film moving amount detector is provided with a microcomputer 28 configuring a setting part for inputting the received light signal before rolling up the film loaded in the camera, and setting threshold values adapted to the levels of the received light signals from plural threshold values having a geometrical progression relation beforehand. A comparator 41 outputs pulses by performing threshold-processing of a received light signal outputted along with rolling-up of the film by a preset threshold value. The microcomputer 28 also configures a detecting part for counting the outputted pulses and detecting the film moving amount.