A multi-piece substrate integrally having a plurality of product regions each provided with a light-emitting element driven by a current and a blank region adjacent to each of the plurality of product regions is prepared. The current is passed through a cathode pad and an anode pad to inspect the light-emitting element. A plurality of display panels are cut out from the multi-piece substrate so as to respectively correspond to the plurality of product regions. The multi-piece substrate includes a plurality of first test pads disposed in each of the plurality of product regions for inspecting the light-emitting element, and a plurality of second test pads disposed in the blank region for inspecting the light-emitting element. The cathode pad and the anode pad are included in the plurality of first test pads and are not included in the plurality of second test pads.