Abstract: Provided is an intra-subject medical system which includes a body-insertable device and a physical quantity generator. The body-insertable device is to be introduced into a subject, is covered by a capsule-shaped exterior member, and includes a physical quantity detecting member which has a directivity to detect a predetermined physical quantity; at least one functional member which has a necessary function for examining or treating inside the subject; and a switch control unit which controls an on/off states or operation mode of the at least one functional member when the physical quantity detecting member detects a physical quantity. The physical quantity generator has a physical quantity emitting unit which emits a temporary physical quantity inside the subject; and a physical quantity direction changing unit which changes an emission direction of the physical quantity.