Provided is a capsule endoscope in which an objective lens unit includes, at the extreme object side, a lens which is a meniscus lens having negative power and disposed with the convex surface thereof towards the object side, so that the convex surface thereof faces the exterior. An illumination unit includes a light source and an illumination window member. The light source is disposed so as to surround the circumference of the lens. The illumination window member is formed in an approximately circular ring shape that surrounds the circumference of the lens and is positioned closer to the image side than an outermost diameter section in the convex surface of the first lens, through which a light flux passes. A light-blocking member that blocks the entry of illumination light into the objective lens unit is disposed between the illumination window member and the lens.
