An antenna to be embedded in a capsule type medical device (21). The antenna includes an antenna conductor (29a29b2952a52b52), and a sheet-like antenna substrate (28a) which at least partly electrically contacts with the antenna conductor (29a29b2952a52b52). The antenna is formed by closely attaching the antenna conductor (29a29b2952a52b52) and the sheet-like antenna substrate (28a).