An optical apparatus including an image forming optical system having a movable optical element, and a driving mechanism which moves the optical element is disclosed. The apparatus comprises a first block which obtains a linear evaluation value by normalizing, by a first tolerance, an aberration expressed by a linear function of a position of the movable optical element out of aberrations of the optical system, and a quadratic evaluation value by normalizing, by a second tolerance, an aberration expressed by a quadratic function of the position out of the aberrations of the optical system, a second block which obtains a minimum value of a dummy variable by linear programming using an upper limit value of the linear evaluation value as the dummy variable, and a third block which determines a position of the optical element to be moved by the driving mechanism so as to minimize a weighted sum of the quadratic evaluation values with respect to a plurality of image heights by using, as the upper limit value of the linear evaluation value, a value prepared by adding a relaxation amount to the minimum value of the dummy variable that is obtained by the second block. The third block minimizes the weighted sum of the quadratic evaluation values by adjusting the weights assigned to the quadratic evaluation values and the relaxation amount.