On adjusting a target specification data error predicted value so as to become larger on detecting maneuver of a target, the target specification data error predicted value is adjusted, in consideration of type of the maneuver and a course of the target, so as to make a direction of varying specification data large and to make a direction of constant specification data small. It is therefore possible to quickly recover a delay of the following of the varying specification data and to avoid increasing an error of the constant specification data.