Coded data corresponding to a partial area is easily generated from coded data of an entire picture. An entropy encoding unit (513) that generates output coded data from input coded data is provided. The input coded data includes image data for a subpicture acquired by dividing a picture and a subpicture header including subpicture identification information generated on a per subpicture basis. The output coded data includes a subpicture parameter set including one or plurality of pieces of subpicture identification information, a subpicture header, and image data for the subpicture.