It is an object of the present invention to obtain a photoelectric conversion device having a favorable spectral sensitivity characteristic and no variation in output current without such a contamination substance mixed into a photoelectric conversion layer or a transistor. Further, it is another object of the present invention to obtain a highly reliable semiconductor device in a semiconductor device having such a photoelectric conversion device. The present invention relates to a semiconductor device including, 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 having a p-type semiconductor layer, an i-type semiconductor layer, and an n-type semiconductor 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.