A chip on film (COF) package includes a film substrate, first leads on a first surface of the film substrate, the first leads having a first length, and second leads on the first surface of the film substrate, the second leads having a second length larger than the first length, first via plugs penetrating the film substrate and connected to first ends of the first leads, and second via plugs penetrating the film substrate and connected to first ends of the second leads, and first connection leads on a second surface of the film substrate facing the first surface, the first connection leads having first ends connected to the first via plugs, and second connection leads on the second surface of the film substrate, the second connection leads having first ends electrically connected to the second via plugs.