1. A position control apparatus comprising: a detecting unit configured to detect a position of a control target; a subtracting unit configured to subtract an output of the detecting unit from a target value; an iterative learning control circuit including a filter into which a deviation between the output of the detecting unit and the target value is input, the iterative learning control circuit feeding forward a control input to the control target; and a parameter computing unit configured to compute a variation in a parameter of the control target; wherein a characteristic of the filter is changed in accordance with the variation in the parameter of the control target.