A battery self-containing body, which self-contains a battery or a battery accommodating body, which accommodates a battery removably is attached to a capsule body including a drive circuit for driving an imaging device and an illuminating device. Thus, the power supply can be turned ON easily. In addition, the inside portion is sealed water-tightly. Thus, the battery self-containing body or a battery can be exchanged easily, which allows the easy reuse. The direction of the visual field of the imaging device is diagonal with respect to the axis of the capsule body. Furthermore, spiral-shape projections are provided on the peripheral surface of the cylinder form. Thus, the rotation allows the surface of canal cavity wall to be examined easily.