A capsule endoscope includes a capsule casing and interior components housed therein whose total specific gravity is set such that the capsule casing floats in liquid introduced into a subject. The capsule endoscope also includes a gravity center position setting unit that sets a position of center of gravity of the capsule casing at a decentered position so that the capsule casing is stabilized in the liquid introduced into the subject without rotating except for rotation about an axis in a direction of the center of gravity and an imager that takes an in-vivo image in a body cavity with an imaging field being set so that a surface of the liquid is out of view when the capsule casing floats in the liquid introduced into the subject in a stabilized posture.
