An optical device including an optical imaging system for forming a real image of an object on a light-receiving surface, the optical imaging system including first and second cylindrical lenses and first and second intermediate lenses, each of the intermediate lenses being composed of a plurality of lens elements arrayed in a line, the first and second cylindrical lenses being opposed to each other so that generatrices thereof are parallel to each other, the first and second intermediate lenses being arranged between the first and second cylindrical lenses in a direction of the generatrices so that a light beam emanated from the object is condensed onto the light-receiving surface through the first cylindrical lens, the first intermediate lens, the second intermediate lens and the second cylindrical lens, wherein each of the lens elements is formed of a one-dimensional binary lens having a light-condensing property only in the direction of the generatrices, whereby a real image by the first and second cylindrical lenses and an erect image by the first and second intermediate lenses are formed perpendicular to each other on the light-receiving surface.