A similar-image detecting part detects similar image regions similar to one another in a plurality of frame images captured by rolling shutter type exposure. A displacement-vector detecting part detects a displacement vector of each of the similar image regions with respect to a reference position in each of the plurality of frame images. An average calculating part calculates an average of displacement vectors in the plurality of frame images. A correcting part shifts a similar image region in one of the plurality of frame images such that the displacement vector of the similar image region becomes the average calculated by the average calculating part.