PURPOSE: To make cable for AC power supply unnecessary by using a solar battery and a storage battery for the power source of a signal generator set on a road.

CONSTITUTION: The power generated by a solar battery in a signal generator set on a road is once charged in a battery, converted to a necessary power for transmission device such as a control circuit, a transmission circuit and a modem etc., by a DCDC converter and supplied. By using a solar battery and a storage battery for a power source in this manner, the cable for AC power supply can be made unnecessary.