Abstract: An electrophotographic copying machine comprises a mouse which is connected to a main unit by a connecting cord and is for inputting positional information for editing. The mouse has a roller whose peripheral side surface is exposed from a case. When the mouse is moved while the peripheral side surface of the roller is brought in contact with a surface of an original, pulses are generated from the mouse attending on rotation of the roller, and these pulses are counted by a counter of a microcomputer. The counted value of the counter is utilized as positional data for editing by the microcomputer. Based on that positional data, the microcomputer partially and selectively lightens of a plurality of LED elements constituting a LED array. Therefore, an electrostatic latent image on a photoreceptor-drum is partially erased so that "masking or "trimming" of an image in an area defined by the positional data is executed.