A producing method includes a bonding process of bonding substrates in a pair one of which has thin film patterns and forming a bonded substrate, a cut forming process of forming a cut line CL1 on a border portion between the mounting area within the panel surface area and other area on the one substrate of the bonded substrate, a cutting process of cutting the bonded substrate into separated bonded substrate pieces, a grinding process of grinding the substrates in a pair that are outside the thin film pattern in each of the separated bonded substrates 50A along the outline and forming edge surfaces of the display panels each having the curved outline, and a removing process of cutting a part of the one substrate along the cut line and removing the part.