A semiconductor device includes a substrate having an insulating surface; a light-transmitting first electrode provided over the substrate; a light-transmitting second electrode provided over the substrate; a light-transmitting semiconductor layer provided so as to be electrically connected to the first electrode and the second electrode; a first wiring electrically connected to the first electrode; an insulating layer provided so as to cover at least the semiconductor layer; a light-transmitting third electrode provided over the insulating layer in a region overlapping with the semiconductor layer; and a second wiring electrically connected to the third electrode.