Patent ID: 7959563

Claim:
A capsule endoscope comprising: an objective lens; light-emitting elements; and a transparent dome that covers an object side of both of the objective lens and the light-emitting elements and is arranged on a most object side in the capsule endoscope, wherein the transparent dome has negative refracting power, and wherein a center of curvature of an object-side surface, which is an outside surface, of the transparent dome disagrees with a center of curvature of an objective-lens-side surface, which is an inside surface facing the objective lens, of the transparent dome, to satisfy the following condition: Rb<L≦Ra where Ra is a radius of curvature of the object-side surface of the transparent dome, Rb is a radius of curvature of the objective-lens-side surface of the transparent dome, and L is a distance from a vertex of the object-side surface of the transparent dome to a most object-side surface of the objective lens.