NOVELTY - The switch has a light emitter (4) with a main body (1) installed at a beam at the pillar of a signal apparatus and oriented in the direction the same as that of the signal apparatus. A solar cell (3) and an electrical storage body (5) is provided in the case (2) of the main body. Light emitting diodes (4a) are provided in front of the main body. The solar cell generates the electromagnetic force for charging the storage body. When power failure of the power supply of the signal apparatus is sensed, the discharge current from the storage body is supplied to switch on or off diodes.    USE - On-off switch for clear recognition of presence of intersection by vehicle driver, especially at time of power failure of power supply of signal apparatus at intersection due to disaster or rolling blackout.    ADVANTAGE - The light emitting diodes of the light emitter can emit and blink e.g. red light, when power supply to the signal apparatus is off, enabling the driver to easily recognize the intersection at time of power failure and safely drive through the intersection, while avoiding occurrence of vehicle accident. The light emitting diodes may be provided on a substrate with a black diode arrangement surface, improving visibility of the light emitter at day time. The use of a Hall electric current sensor for power failure detection allows the switch to be installed easily about the signal apparatus. Since the electrical storage body uses a lithium ion capacitor with high output, high energy density and outstanding self-discharge property, durability and reliability of the electrical storage body can be ensured, while stable, safe electrical storage or discharge of the body can be ensured even during summer.    DESCRIPTION OF DRAWING(S) - The drawing shows the expanded sectional view of an on-off switch for clear recognition of an intersection.    Main body (1)    Case (2)    Solar cell (3)    Light emitter (4)    Light emitting diodes (4a)    Electrical storage body (5)