An image evaluation device, comprising: an encoding unit (24, 334) configured to encode an object image that is one of a plurality of encoded images that include three or more time-series encoded images obtained by imaging the same spatial region, and reference images that are images other than the object image among the plurality of images; a difference determination unit (25, 335) configured to determine for each region corresponding to a coding unit of the object image, the presence or absence of a difference between a small image of said region and the small images of the adjacent regions on the basis of a difference between the amount of coding bits by the encoding unit (24, 334) of the region of the object image and the amount of coding bits of the adjacent regions, wherein the difference determination unit (25, 335) is configured to determine, if the presence of a difference is determined, the presence or absence of a further difference between the small image and the small images, spatially having the same position as the small image of the object image, of each region corresponding to a coding unit of each of the reference images, respectively, based on an amount of coding bits by the encoding unit (24, 334) of the small image of the object image and the amount of coding bits of the small image of the reference images; and an evaluation index acquisition unit (26, 336) configured to acquire a determination result of determining a presence or absence of a difference between the small image of the each region within the object image and the small images of the each region within each of the reference images, and acquire an evaluation index for each region within the object image based on the determination results, wherein the evaluation index acquisition unit (26, 336) is configured to obtain a result of determining the number of pairs of regions determined to have the difference between small images among a plurality of pairs of a region within the object image and each of regions, spatially having the same position as the small image of the object image, within the reference images as the evaluation index, said evaluation index assigning a priority indicating which region is preferentially selected for image processing, wherein an higher evaluation index indicates higher accuracy in the difference determination result, and the image evaluation device further comprises an image processing unit configured to perform image processing, in which the small images are displayed differently according to the evaluation index for each region, on each of the small images of regions within the object image. an encoding unit (24, 334) configured to encode an object image that is one of a plurality of encoded images that include three or more time-series encoded images obtained by imaging the same spatial region, and reference images that are images other than the object image among the plurality of images; a difference determination unit (25, 335) configured to determine for each region corresponding to a coding unit of the object image, the presence or absence of a difference between a small image of said region and the small images of the adjacent regions on the basis of a difference between the amount of coding bits by the encoding unit (24, 334) of the region of the object image and the amount of coding bits of the adjacent regions, wherein the difference determination unit (25, 335) is configured to determine, if the presence of a difference is determined, the presence or absence of a further difference between the small image and the small images, spatially having the same position as the small image of the object image, of each region corresponding to a coding unit of each of the reference images, respectively, based on an amount of coding bits by the encoding unit (24, 334) of the small image of the object image and the amount of coding bits of the small image of the reference images; and an evaluation index acquisition unit (26, 336) configured to acquire a determination result of determining a presence or absence of a difference between the small image of the each region within the object image and the small images of the each region within each of the reference images, and acquire an evaluation index for each region within the object image based on the determination results, wherein the evaluation index acquisition unit (26, 336) is configured to obtain a result of determining the number of pairs of regions determined to have the difference between small images among a plurality of pairs of a region within the object image and each of regions, spatially having the same position as the small image of the object image, within the reference images as the evaluation index, said evaluation index assigning a priority indicating which region is preferentially selected for image processing, wherein an higher evaluation index indicates higher accuracy in the difference determination result, and the image evaluation device further comprises an image processing unit configured to perform image processing, in which the small images are displayed differently according to the evaluation index for each region, on each of the small images of regions within the object image.