Widening an angle of view, and obtaining a clear image with no distortion by sufficiently correcting an aberration caused by widening the angle of view.A capsule endoscope 10 is provided with an imaging lens 20, capsule body 22, and a transparent cover 23. The capsule body 22 is formed hollow, and has an opening 22b at its end 22a. The imaging lens 20 is provided such that a part thereof is positioned inside the capsule body 22 and the rest is protruded from the opening 22b. The transparent cover 23 is formed into a dope shape, and is attached to the end 22a of the capsule body 22 to cover the imaging lens 20 protruded from the opening 22b. The inside of a patients body is captured using the transparent cover 23 and the imaging lens 20 designed to satisfy the following condition: fD/fL≤70where fD is a focal length of the transparent cover 23, and fL is a focal length of the imaging lens 20.
