To provide an improper exposure detecting unit which can properly detect an overexposure and underexposure corresponding to the film speed.

A range finding part 20 measures the distance to a subject. A CPU 31 detects overexposure or underexposure when the measurement result of the range finding part 20 is not within a distance range based upon a permissible exposure range determined on the basis of a proper exposure value corresponding to the speed of a film loaded in a camera. The permissible exposure range is so determined that the difference between the maximum value or minimum value of the permissible exposure range and the proper exposure value is different corresponding to the speed of the film loaded in the camera.