An inductor element 100 capable of functioning properly on a substrate includes two similarly shaped conductors such as spiral conductors 120, 122 formed on the surface of a semiconductor substrate 110. A round hole portion is provided near the center of a base member for fixing the light guide, and slit portions are provided on both ends thereof. The cooling plate and an associated internal cover plate have a combined shape optimized for guiding the air flow between the fan and the cooling opening.