An input device capable of lowering the vertical position of light beams traveling within the frame of a frame-shaped optical waveguide without using optical path conversion is provided. The input device includes a light-emitting module incorporating a light-emitting element connected to light-emitting cores of the optical waveguide, and a light-receiving module incorporating a light-receiving element connected to light-receiving cores of the optical waveguide. A section of the optical waveguide on a light-receiving side, in which the light-receiving cores are formed, is placed upside down so that an over cladding layer is positioned on the underside. Accordingly, the light-receiving module is also placed upside down. Thus, the light-receiving module protrudes along the height thereof in such a manner that the amount of downward protrusion is less than the amount of upward protrusion.