An in-vivo information acquiring system includes a body-insertable apparatus that transmits a wireless signal containing an in-vivo image, and a receiving apparatus that receives the wireless signal. The body-insertable apparatus includes an imaging unit, a selecting unit, and a transmitting unit. The imaging unit captures in-vivo images. The selecting unit selects an in-vivo image to be added with unique information from the in-vivo images. The transmitting unit additionally arranges an identification signal, which is written according to a signal sequence rule of synchronization signals added to scanning line information about the in-vivo image selected by the selecting unit, in a position corresponding to positions in which the synchronization signals are arranged, adds unique information corresponding to the identification information after the identification information, and transmits the in-vivo image added with the unique information.