A paper detecting device to detect paper presence on a paper plate in a paper feeding cassette, and comprising a light-emitting device and a light-receiving sensor. In the paper feeding cassette, an end-fence is movably mounted, and at least one of the light-emitting device and the light-receiving sensor is mounted on a base of the end-fence to be covered by the stacked paper. Accordingly, before developing a new image, the complete consumption of the paper supply can be detected, and therefore, the toner can be saved.