An embodiment of the present invention provides a display device including a substrate and a transistor on the substrate. The transistor includes: a lower layer having conductivity and including a body portion and a plurality of protrusions; an oxide semiconductor layer including a channel region, a first conductive region disposed at a first side of the channel region, and a second conductive region disposed at a second side of the channel region, where the second side is opposite the first side; a gate electrode overlapping the channel region in a plan view; a first electrode electrically connected to the first conductive region; and a second electrode electrically connected to the second conductive region. The plurality of protrusions protrudes from the body portion, and the body portion overlaps the channel region in the plan view.