An image compositing device for generating a composite image corresponding to a predetermined time section with use of at least a plurality of photographed images continuously shot at a predetermined time interval during the predetermined time section, wherein said predetermined time interval is constituted by an exposure time section during which exposure of an image sensor to capture one of said plurality of photographed images occurs and a non-photographing time section which corresponds to a time interval between an end of the exposure time section and a start of a next exposure time section, the image compositing device comprising: an interpolation unit adapted to be connected to a memory which stores a plurality of photographed images continuously shot at a predetermined time interval during a predetermined time section, adapted to determine, in accordance with a duration of the exposure time section and a duration of the non-photographing time section, a number of interpolation images to interpolate in each of the non-photographing time sections of the predetermined time section, adapted to generate the determined number of interpolation images for each non-photographing time section, with at least use of the stored photographed images in both exposure time sections temporally adjacent to said each non-photographing time section, and adapted to store said generated interpolation images in the memory; and a compositing unit adapted to be connected to the memory and to generate a composite image corresponding to the predetermined time section, by obtaining from the memory, the interpolation images generated by the interpolation unit for the non-photographing sections of said predetermined time section, by obtaining from the memory, the plurality of photographed images photographed during said predetermined time section, and by adding respective pixels situated in a same position in said plurality of photographed images and said interpolation images. an interpolation unit adapted to be connected to a memory which stores a plurality of photographed images continuously shot at a predetermined time interval during a predetermined time section, adapted to determine, in accordance with a duration of the exposure time section and a duration of the non-photographing time section, a number of interpolation images to interpolate in each of the non-photographing time sections of the predetermined time section, adapted to generate the determined number of interpolation images for each non-photographing time section, with at least use of the stored photographed images in both exposure time sections temporally adjacent to said each non-photographing time section, and adapted to store said generated interpolation images in the memory; and a compositing unit adapted to be connected to the memory and to generate a composite image corresponding to the predetermined time section, by obtaining from the memory, the interpolation images generated by the interpolation unit for the non-photographing sections of said predetermined time section, by obtaining from the memory, the plurality of photographed images photographed during said predetermined time section, and by adding respective pixels situated in a same position in said plurality of photographed images and said interpolation images.