PURPOSE: To enable an operator to safely and rapidly get off on the ground from the driving cab even if it is dark in the surrounding, by providing a light illuminating the descending way and a light controller lighting for a specified period in a specified condition.

CONSTITUTION: When an operator turns off a key switch 13 to stop the engine, the key switch 13 is connected to a terminal (a). Next, when the operator opens the door 5 of the driving cab 4 to get off therefrom, a door switch 14 is turned on. In this case, a main switch 16 is closed. Next, the actuation condition of a timer 15 becomes effective by changingover of the key switch 13 and the door switch 14 and then the illuminators 9, 10 are turned on and the time of the timer 15 starts counting. Accordingly, a ladder 2, a cat walk 6, a stay 7, and a step 8 are illuminated brightly by the illuminators 9, 10. This condition is kept while the timer continues the counting work and after a specified time interval, the illuminators are put off.