PURPOSE: To provide a thin input coordinate detector which does not need any exclusive input panel by setting the rotatable light receiving means at two positions of an optional input area to secure the directive characteristic and the photoelectric converting function and then calculating the coordinate position of an input means containing a light emitting means in the input area.

CONSTITUTION: An input pen 1 incorporates a light emitting element 1A at its tip part. The rotary motors 3A and 3B are set at each prescribed part of an input area 4, and the light receiving elements 2A and 2B are fixed to the motors 3A and 3B respectively to receive the light sent from the element 1A. The directions of both element 2A and 2B revolved by the motors 3A and 3B can be optionally set within the plane of the area 4. The photodetecting sensitivity of both elements 2A and 2B have the directivity and therefore the coordinate position of the pen 1 is calculated based on the rotational angle information θ1 and θ2 on both motors 3A and 3B which are secured when both elements 2A and 2B receive the light from the element 1A.