Disclosed is a thin film transistor including both an N-type semiconductor layer and a P-type semiconductor layer, a method for manufacturing the same, and a display device including the same, wherein the thin film transistor may include a first gate electrode on a substrate; a first gate insulating film covering the first gate electrode; a semiconductor layer on the first gate insulating film; a second gate insulating film covering the semiconductor layer; and a second gate electrode on the second gate insulating film, wherein the semiconductor layer includes the N-type semiconductor layer and the P-type semiconductor layer.