An in-vivo observing system for observing inside of a subject includes an illuminating unit configured to illuminate inside of the subject by illumination light; an imaging unit configured to sequentially capture in-vivo images of the subject illuminated by the illumination light; a direction change unit configured to change an image capturing direction of the imaging unit; and a control unit configured to control the direction change unit to set an angular difference in the imaging capturing direction less than an angle of view of the imaging unit when the imaging unit captures two continuous in-vivo images while causing the direction change unit to change the image capturing direction.