(Amended) A lighting control system for use on a vehicle, the vehicle comprising a motorcycle having a front wheel steerable by a handle assembly, comprising: a winker switch and a hazard switch, which can be turned on and off selectively by a driver of the vehicle; and a controller, which operates in a winker mode for blinking either left or right lighting bodies (LF, LR, RF, RR) having light-emitting diodes (LF-LED, LR-LED, RF-LED, RR-LED) mounted on left and right sides of the vehicle when the winker switch is turned on, and a hazard mode for blinking the left and right lighting bodies (LF, LR, RF, RR) simultaneously when the hazard switch is turned on, the controller comprising a left switch input port for supplying signals representative of operation of the left lighting bodies (LF, LR), and a right switch input port for supplying signals representative of operation of the right lighting bodies (RF, RR), the winker switch and the hazard switch being connected through common wires to the left switch input port and the right switch input port, the winker switch and the hazard switch being connected between the controller and a power supply, the winker switch and the hazard switch being disposed on a switch case provided proximate to the handle assembly, the hazard switch comprising a three-contact switch, three contacts of which are connected to the left switch input port, the right switch input port, and the power supply, respectively, when the hazard switch is turned on; and judging means for determining an input signal supplied from the left switch input port and an input signal supplied from the right switch input port when the winker switch is turned on or when the hazard switch is turned on, the judging means being connected between the winker and hazard switches (WS, HS) and the left and right lighting bodies (LF, LR, RF, RR), characterised in that the judging means determines that the hazard switch has been turned on if the judging means detects an input signal from either one of the left switch input port and the right switch input port and then, within a prescribed time, detects an input signal from the other of the left switch input port and the right switch input port, and further determines that the winker switch has been turned on if the judging means does not detect, within the prescribed time, an input signal from the other of the left switch input port and the right switch input port, and the controller supplies the light-emitting diodes (LF-LED, LR-LED, RF-LED, RR-LED) with electric power based on the judgment by the judging means that the hazard switch and the winker switch are turned on. a winker switch and a hazard switch, which can be turned on and off selectively by a driver of the vehicle; and a controller, which operates in a winker mode for blinking either left or right lighting bodies (LF, LR, RF, RR) having light-emitting diodes (LF-LED, LR-LED, RF-LED, RR-LED) mounted on left and right sides of the vehicle when the winker switch is turned on, and a hazard mode for blinking the left and right lighting bodies (LF, LR, RF, RR) simultaneously when the hazard switch is turned on, the controller comprising a left switch input port for supplying signals representative of operation of the left lighting bodies (LF, LR), and a right switch input port for supplying signals representative of operation of the right lighting bodies (RF, RR), the winker switch and the hazard switch being connected through common wires to the left switch input port and the right switch input port, the winker switch and the hazard switch being connected between the controller and a power supply, the winker switch and the hazard switch being disposed on a switch case provided proximate to the handle assembly, the hazard switch comprising a three-contact switch, three contacts of which are connected to the left switch input port, the right switch input port, and the power supply, respectively, when the hazard switch is turned on; and judging means for determining an input signal supplied from the left switch input port and an input signal supplied from the right switch input port when the winker switch is turned on or when the hazard switch is turned on, the judging means being connected between the winker and hazard switches (WS, HS) and the left and right lighting bodies (LF, LR, RF, RR), characterised in that the judging means determines that the hazard switch has been turned on if the judging means detects an input signal from either one of the left switch input port and the right switch input port and then, within a prescribed time, detects an input signal from the other of the left switch input port and the right switch input port, and further determines that the winker switch has been turned on if the judging means does not detect, within the prescribed time, an input signal from the other of the left switch input port and the right switch input port, and the controller supplies the light-emitting diodes (LF-LED, LR-LED, RF-LED, RR-LED) with electric power based on the judgment by the judging means that the hazard switch and the winker switch are turned on.