<p>There are provided a first switch (11) which is switched to the on state or the off state in association with a displacement of an actuator (1) which causes a displacement by a contact with an object and a second switch (12) which is switched to the on state or off state later than the first switch in association with the displacement of the actuator. A switch output is produced and an abnormality is detected in accordance with the on and off states of these switches.</p>
