In order to minimize a calculation load and surely obtain a maximum adhesion torque, estimated adhesion torques are always stored, an maximum value is obtained from the stored plural estimated adhesion torques immediately before slip/ skid is detected when detecting the slip/ skid, and the maximum value is set as a maximum adhesion torque. The maximum adhesion torque immediately before the slip/ skid is detected is compared with a value of the estimated adhesion torque when the slip/ skid is detected. When the calculated value exceeds a threshold value, it is determined as a condition where an adhesion coefficient drastically drops, and a suppression/return ratio of the torque is switched to a lower value than that under a condition where the adhesion coefficient does not drastically drop. The value of the torque at the time of suppression or return is set to a smaller value to surely suppress the slip/ skid.