A system for controlling the coating width of an electrode plate, The system includes: a coating device which ejects a paste at a predetermined width from each of a plurality of slit nozzles toward a fed core substrate to form a coating layer on the surface of the core substrate; a gap controlling device which controls the gap between the slit nozzles of the coating device and the core substrate; a coating width measuring device which measures the width of the coating layer on the surface of the core substrate; and a controlling unit which controls the gap controlling device based on the results obtained by comparing the measured coating width with a predetermined coating width. In this system, the stripe-shaped coating layer is formed without using a masking tape, and the width of the coating layer is controlled with high accuracy.