In a capsule casing 16 as an exterior case that includes end cover casings 16a and 16b and body cover casings 16a and 16b, planar portions 16f and 16g are formed at portions of a circumferential surface of the body cover casings 16c and 16d, and imaging units 14a and 14b are arranged inside the capsule casing 16 at positions at which imaging inside of body cavities of a subject is possible through the planar portions 16f and 16g, thereby preventing a lens effect, eliminating image failures to improve images, and enhancing image quality.
