To detect the input positions of respective contact points with high accuracy even when using a light guide plate enabling a multi-point simultaneous input and even when a plurality of contact points are present at the same coordinates position.

A control unit 5e as control means identifies a position of an input to a touch area 2a by a fingertip 10, etc. as a contact object according to a coordinate when a light reception element 4 as light reception means receives scattered light and coordinates of a light emission element 3 as a light emission means that is made to, for example, perform lighting scanning when the light reception means 4 receives the light, and performs control to lower a threshold during receiving the scattered light of the light reception element 4 corresponding to one contact point if there is the one contact point between the other contact point and the light emission element 3 or the light reception element 4 when there are a plurality of contact points by the fingertip 10, etc., on the same coordinates of one coordinates and/or the other coordinates.