In an optical unit including a photoelectric conversion chip adapted to be optically connected to an optical fiber, and a semiconductor chip for driving the photoelectric conversion chip, both the photoelectric conversion chip and the semiconductor chip are wrapped with a flexible sheet, to thereby produce an enveloper enveloping the photoelectric conversion chip and the semiconductor chip therein. At least a part of the enveloper is formed as a transparent area for allowing an optical connection between the optical fiber and the photoelectric conversion chip.