To prevent the occurrence of a stick slip when a torque diode inserted to an irreversible rotation transmission system is locked off by an increase of input torque from 0 to a target value.

When a torque diode transmits target torque from an input shaft to an output shaft, and at lock-off in the case of a rotational direction is the same rotational direction of the output shaft by load torque, the last standard response calculation part 96 may not unconditionally make a crank shaft rotation angle command value dθ_0 for a basic standard response as a crank shaft rotation angle command value dθ for the last standard response and sets an upper limit to dθ=dθ_min so that dθ may not be larger than a crank shaft rotation angle command value dθ_min of a minimum speed standard response for stick slip prevention. The stick slip of the torque diode can be prevented as the transient response of dθ against a crank shaft rotation angle target value tθ may not be lower than a speed lower limit for preventing a stick slip which is determined by a speed change of dθ_min.