A light emitter is operable to emit light. A light receiver is adapted to receive the light emitted from the light emitter, and operable to output a signal in accordance with an amount of the received light, thereby detecting a position of an object. At least one transparent member is disposed between the light emitter and the light receiver. A first line pattern is provided with the transparent member so as to oppose the light emitter, and includes first light transmitting sections and first light shielding sections which are alternately arranged in a first direction with a first pitch. A second line pattern is provided with the transparent member so as to oppose the light receiver, and includes second light transmitting sections and second light shielding sections which are alternately arranged in the first direction with a second pitch. Each of the first light transmitting sections is adapted to allow the light emitted from the light emitter to pass through. Each of the first light shielding sections is adapted to shield the light emitted from the light emitter. Each of the second light transmitting sections is adapted to allow light having passed through the transparent member. Each of the second light shielding sections is adapted to shield the light having passed through the transparent member.