A controller controls right and left wheel drive motors based on a tire angle detected by a tire angle sensor such that the angular velocities of a pair of drive wheels about the center of a turn of the vehicle are equal to each other. The controller determines a steering speed of a steered wheel at the time a steering wheel is turned, from the tire angle detected by the tire angle sensor. Based on the steering speed, the controller controls a hydraulic pressure control motor, enabling a hydraulic pump to supply working fluid at a rate corresponding to the steering speed through a priority valve to a steering cylinder. With this arrangement, the vehicle is allowed to make a smooth turn.