PURPOSE: To shorten a time required for turning action of a working vehicle by simultaneously performing at least a part of these action of lowering down a lift type grounding unit and operation of steering to a turning direction side of a steering wheel, by a control means.

CONSTITUTION: A lift type grounding unit of floating/grounding a pair of right/ left driving rear wheels 1R, 1L from/to the ground surface is provided and controlled to be lifted by a control unit. First, the lift type grounding unit 9 in a turning center side is lowered down, and in order to turn a car body V, steering is operated of a steering front wheel 1F to further control the propelling rear wheels 1R, 1L. Action of lowering down the lift type grounding unit 9 and operation of the steering front wheel 1F are simultaneously performed at least a part by a control means. That is, the lift type grounding unit in the turning center side is lowered down, simultaneously to perform steering operation by a steering motor M1, and next, the driving rear wheels 1R, 1L not in the turning center side are driven and turned with the lift type grounding unit 9 serving as the center.