Abstract: An object detecting optical unit for detecting a direction or a position of an object placed on a detecting plane surface is disclosed. The optical unit detects existence or non existence of a retroreflective light reflected by a retroreflective member. A light projection device is formed by a plurality of light sources and corresponding lenses, arranged in to form a fan shaped projection pattern parallel to the detecting plane surface, the projection pattern being as if projected from a virtual one point light source. A light receiving device is included which has a slit or lens and linear photoreceptive group, arranged in such a manner as to form a light receiving pattern with a view field corresponding to the fan shaped projection pattern. A position coordinate input apparatus using the optical unit is also disclosed.