A display device is disclosed. In one aspect, the display device includes a display area configured to display an image, a peripheral area neighboring the display area, and at least one test element group (TEG) including a test thin film transistor (TFT) formed in the peripheral area and a plurality of test pads electrically connected to the test TFT. The display device also includes first to third dummy circuits separated from the test TFT, each of the first to third dummy circuits including a plurality of first dummy semiconductor layers and a plurality of first dummy gate electrodes overlapping at least a portion of the first dummy semiconductor layers in the depth dimension of the display device.