A body-insertable apparatus is introduced in a subject to perform at least one of input and output of a predetermined fluid to and from the subject. The body-insertable apparatus includes a reservoir (2) in which the predetermined fluid is stored； a first communicating channel (4) whose one end is opened to an inside of the reservoir, the first communicating channel (4) being extended in a predetermined direction； a second communicating channel (5) whose one end is opened to an outside space of the body-insertable apparatus, the second communicating channel (5) being extended in a direction substantially parallel to the first communicating channel (4), and the second communicating channel (5) partially running parallel to the first communicating channel (4)； and a control mechanism (6) which controls a communication state between the first communicating channel (4) and the second communicating channel (5).
