It is an exemplified object of the present invention to provide an optical unit that can easily and inexpensively align an optical axis of the lens and a beam from a light source during continuous operation, and to provide an electrophotographic recording device that has such an optical unit and thereby can form a high-quality latent image on a photosensitive body. The optical unit as an exemplified embodiment of the present invention is configured to have the optical axis of the lens and a mounting position thereof substantially aligned with each other, and thus reduce or eliminate a misalignment of the optical axis with the light source and lens even if temperature rises.