1. An imaging device comprising: a detecting unit that detects a first motion vector in an image that is obtained via an imaging system that can perform zooming; a storage unit that stores in advance a second motion vector caused by performing zooming of the image, wherein the second motion vector is determined by a rate of change of the viewing angle; and a calculating unit that calculates a third motion vector from the first motion vector and the second motion vector, wherein the third motion vector is a motion vector where influence by performing zooming of the image is reduced.