A device that combines a first image photographed with a first amount of exposure and a second image photographed with a second amount of exposure lower than the first amount of exposure, thereby generating a combined image having a wider dynamic range than a dynamic range for the amounts of exposure of the first and second images, the device includes a motion region extraction unit configured to extract at least one motion region in which an object moving between the first image and the second image is shown; a combining ratio determining unit configured to increase a combining ratio of the second image to the first image for a pixel in a background region outside of the at least one motion region such that the higher a luminance value of a pixel of the first image, the higher the combining ratio.