A display panel manufacturing method in which forming a thin film on a substrate and etching the thin film are repeated a plurality of times to form on the substrate a plurality of scanning signal lines, a plurality of video signal lines that three-dimensionally intersects the plurality of scanning signal lines with an insulating layer between them, and TFT elements and pixel electrodes each disposed in a pixel area enclosed with two adjacent scanning signal lines and two adjacent video signal lines. The method also includes: exposing a resist film using exposure dimensions numerically expressed based on design patterns prepared in advance; etching the thin film using etching resists formed by developing the exposed resist film so as to form thin-film patterns; and correcting the design patterns according to the complete dimensions of the formed thin-film patterns.