a fixed value is subtracted from the integrated value errorivn of the vn deviation error as a result after the feedback control is switched from the vn control to the wg control the amount of vn control is gradually subtracted from the amount of control immediately before the switch specifically even after the feedback switches to the wg control on maintaining the vn control at the amount immediately before the switch along with the increase in the amount of exhaust gas flow the flow velocity in the introductory channel 40 increases and the pressure drops as a result of this pressure drop a movable flapper 45 is swung in the direction which closes the introductory passage 40 and the capacity of the turbocharger is reduced on the other hand when the fixed value is subtracted from errorivn that is the accumulated value of the vn deviation error the movable flapper 45 is swung in the direction which cpens the introductory passage 40 the passage 40 is completely opened so that even when wg control is entered a sufficient volume of exhaust gas can be maintained and the turbocharger is able to demonstrate maximum restriction performance however in the case where fp2fbvnwg is 34 0 34 the program proceeds to 134 where the i portion of the vn control is obtained from the calculation kivn u00d7 errorivn and this is added to m2 here kivn is the computed integrated gain in addition at the same time.