The driven rotation axis, the driving rotation axis, the ACT lever, the driving pin, the rod, the driven pin and the WGV lever constitute a linkage. In order to consider the instrumental error caused by the linkage configuration, a link ratio is defined by the equation (Link ratio=(Lwg/Lact)*(sin β/sin α), wherein Lwg is a length of the WGV lever, Lact is length of the ACT lever, β is an angle formed by the WGV lever and the rod, and α is an angle formed by the ACT lever and the rod). The current value input to the DC motor is corrected with a correction coefficient is a value obtained by dividing an actual link ratio by a target link ratio.