When a wheel slip value of the driven wheel relative to a surface of road becomes excessive during acceleration, torque to be applied to the driven wheels is controlled by the traction control so as to make the actual wheel slip value of the driven wheel become a predetermined target value. There is counted the duration of time during which the actual wheel slip value of the driven wheel becomes smaller than a predetermined threshold value set as a value smaller than the target value, and a control value for the traction control is corrected in accordance with the duration of time counted. This correction is implemented so as to increase the torque to be applied to the driven wheels larger as the duration of time counted becomes longer. The control value to be corrected includes the target value itself or a road surface friction coefficient .mu. as a parameter for setting the target value.