Wheel drive motors (8) constituted of electric motors for driving rear wheels (7) are provided on a vehicle body (2) of a dump truck (1). Each wheel drive motor (8) is connected to a main power generator (12) through a bidirectional converter (20) and the like and driven by power supplied from the main power generator (12). A resistor (21) that consumes regenerative power from each wheel drive motor (8) is connected to the bidirectional converter (20). Cooling air is supplied to the resistor (21) from a blower (24). Operations of a switch (23) of the resistor (21) and the blower (24) are controlled by a controller (28). A mode selecting switch (29) for selecting a heating mode (A), a blowing mode (B), and a heating and blowing mode (C) is connected to the controller (28).