A thin film transistor includes a substrate; an active layer including a channel area, a first conductive area, and a second conductive area; a gate insulating layer on a portion of the active layer; a first through hole penetrating through a portion of the first conductive area; a second through hole penetrating through a portion of the second conductive area; a gate electrode overlapping the channel area of the active layer; a first electrode electrically connected to the first conductive area; and a second electrode electrically connected to the second conductive area. One side of the first electrode adjacent to the first through hole is parallel to the one side of the first through hole, the first electrode including protrusion parts at both ends thereof and a groove part concavely recessed from the gate electrode.