An intra-subject position display system for displaying a position of an intra-subject device, which is introduced into a subject and moves therein, wherein a relative position of the intra-subject device to an outer surface of the subject is detected and displayed. The position of the intra-subject device is displayed in a relation with the outer surface of the subject. Thereby, it is possible to easily determine in which site of the subject the intra-subject device exists. The present invention is effective to recognize a position of, for example, a capsule type endoscope or a test capsule therefor in the subject (e.g., a human body). To recognize the outer surface of the subject, for example, a plurality of radio devices are arranged on the outer surface of the subject and their radio signals are analyzed.