In an electronic control unit 31, a duty conversion map 41 from which a driving duty in energizing and driving an electromagnetic coil, not shown, of an electromagnetic vacuum adjustment valve 12 on the basis of a variable equivalent to target quantity of feedback of exhaust gas, for example, the magnitude of a desired negative pressure to a negative pressure output port (not shown) of the electromagnetic vacuum adjustment valve 12, and a duty correction map 42 from which a correction value for the driving duty is acquired on the basis inputted battery voltage and engine cooling water temperature, are provided. The driving duty is multiplied by the correction value acquired from the duty correction map 42, and on the basis of the corrected driving duty, energization to the electromagnetic vacuum adjustment valve 12 is performed by a driving circuit 26.