A manufacturing method of a display device includes forming a pixel in a display area of a panel, forming a transistor circuit in a peripheral area of the panel, the peripheral area being located in the vicinity of the display area, forming a first pad in a part of the peripheral area, forming a second pad in a peripheral area of another panel adjacent to the part of the panel, the second pad being electrically connected to the transistor circuit, performing a driving inspection on the transistor circuit by use of the second pad, and separating the first pad and the second pad from each other after the driving inspection.