PURPOSE: To obtain an optical coordinate input device which can highly precisely execute input in a wide range.

CONSTITUTION: Rectangular spot images are formed in light-receiving elements 11 and 12 by arranging mask boards 71 and 72 provided with rectangular holes between the light-receiving elements 11 and 12 consisting of two division photodiodes and lenses 21 and 22. Thus, a ratio between the difference and the sum of two outputs in the light-receiving elements 11 and 12 can accurately be made proprotional to the tangent of the incident angle of light from a light- emitting element 1 in the whole area of a coordinate input possible range. Thus, the coordinate of the light-emitting element 1 can accurately be calculated and the coordinate can highly precisely be inputted in the wide range. Then, the wide coordinate input possible range can be obtained by setting the distance 1 between the light-receiving elements 11 and 12 and the lenses 21 and 22 to be less than half the focal distance of the lenses 21 and 22.