When a fiber optical plate is applied to a touch sensor, a flat touch surface can be formed, and the overall device using the fiber optical plate can be formed into a low-profile structure. The numerical aperture of the input end face of one slant FOP is set to be larger than that of the output end face of another slant FOP to cause light incident from the latter slant FOP to be efficiently incident on the former slant FOP. The detection surface and the output end face are located to be orthogonal to each other. With this structure, the detection surface can be formed evenly with the touch surface. In addition, detection elements such as a CCD can be disposed at the output end face along the lower surface of the touch surface.