Due to convergent distance sensing, the color or material of the object has almost no effect. Further, the background also has very little effect, enabling stable sensing. The spot-beam type Panasonic EX-43T sensor is incorporated with an OFF-delay timer. The variable OFF-delay timer is useful for detecting a printed circuit board regardless of small holes, cutouts, or electronic parts on it. Even in a limited sensing area, the sensor is not affected by small perforations or unevenness. It is suitable for presence detection.