A motion vector measurement condition setting unit determines a measurement precision, which is used when measuring a motion vector between a plurality of images, on the basis of information indicating a distortion in an optical system and sets a plurality of motion vector measurement regions in which the motion vector is to be measured on an image. A motion vector calculation unit determines the motion vector between the plurality of images in each of the plurality of motion vector measurement regions at the determined measurement precision. A motion vector integration processing unit determines a positional displacement amount between the plurality of images on the basis of the motion vector determined in each of the plurality of motion vector measurement regions.