To provide a method for reducing air resistance and rolling resistance of an electric vehicle or the like.

The coefficient of travel resistance is reduced by positively making travel wind flow below a flattened vehicle floor; and a lift force generating mechanism to generate lift force by the travel wind under the floor is disposed, the lift force controlled to be within a range not decreasing stability of travelling, particularly during high-speed traveling, so that vehicle grounding load is reduced, that is, the rolling resistance is decreased by the lift force. The quantity of generating the lift force by the lift force generating mechanism is variable according to changes in the vehicle weight or the like.