transfer torque based on the actuator stroke is predicted in the idle state of the engine i e on a region where the engine torque is lowest in the first driving process s 20 and the first predicting process s 30 first and then on a region where the engine torque is a bit higher in the second driving process s 70 and the second predicting process s 80 thus the second driving process s 70 and the second predicting process s 80 are repetitively performed while the torque restriction value of the torque restricting process s 60 is raised step by step thereby the clutch transfer torque based on the actuator stroke on a region where the torque is raised step by step is stored then the clutch transfer torque based on the actuator stroke can be obtained on all the desired engine torque regions in repetitively performing the second driving process s 70 and the second predicting process s 80 a second disengaging process s 90 of disengaging the clutch is performed before the second driving process s 70 is performed again after the second predicting process s 80 is performed the torque restriction value is set so as to allow all desired engine torque regions to be divided by a desired number using a test and analysis however it may be preferable to prevent a time required to predict the clutch transfer torque from being too long by dividing the regions into an excessive.