An object of the present invention is to enable a receiving side to easily recognize which of imaging devices has picked up received image data. A capsule endoscope 3 (one example of the in-vivo image acquiring apparatus) of the present invention is swallowed by a subject, and picks up images of the inside of organs of the subject. The capsule endoscope 3 has a plurality of LEDs 11a, 11b, a plurality of CCDs 12a, 12b, and a transmission module 46. The CCDs 12a, 12b paired with the LEDs 11a, 11b pick up images of the inside of a body cavity illuminated by the LEDs 11a, 11b. The transmission module 46 adds identification data for identifying the CCDs 12a, 12b to image data in front and rear directions of the capsule endoscope 3 picked up by the CCDs 12a, 12b, and transmit the image data together with the identification data to the receiving side.
