A driving thin-film transistor can include a substrate; a first active layer disposed on the substrate and including a first protruding portion; a second active layer overlapping with the first active layer and including a second protruding portion; a gate electrode disposed between the first active layer and the second active layer; a source electrode connected to the first protruding portion of the first active layer; and a drain electrode connected to the second protruding portion of the second active layer, in which the first protruding portion of the first active layer and the second protruding portion of the second active layer are located at different positions.