An image coding device (300) according to the present invention includes: a signal division unit (302) which divides each of pictures included in an input image signal (310) into a first coding target region (315A) and a second coding target region (315B); a first coding unit (303A) which codes the first coding target region (315A) to generate a first coded signal (313A); a second coding unit (303B) which codes the second coding target region (315B) to generate a second coded signal (313B); and a signal combining unit (307) which combines the first coded signal (313A) and the second coded signal (313B) to generate an output coded signal (314), wherein the signal division unit (302) determines, as a range to be used for motion vector search by the first coding unit (303A), a range including the first coding target region (315A) and a first overlap region (316A), and changes a size of the first overlap region (316A) according to a predetermined condition.