Techniques are provided for obtaining a photoelectric conversion device having a favorable spectral sensitivity characteristic and reduced variation in output current without a contamination substance mixed into a photoelectric conversion layer or a transistor, and for obtaining a highly reliable semiconductor device including a photoelectric conversion device. A semiconductor device may include, over an insulating surface, a first electrode; a second electrode; a color filter between the first electrode and the second electrode; an overcoat layer covering the color filter; and a photoelectric conversion layer over the overcoat layer, where one end portion of the photoelectric conversion layer is in contact with the first electrode, and where an end portion of the color filter lies inside the other end portion of the photoelectric conversion layer.