A capsule endoscope is disclosed that includes a capsule and a transparent cover having a central axis and that is located in front of an objective optical system within the capsule. The objective optical system has a depth of field, a field of view, and an image surface that has curvature of field, and is arranged on the central axis of the transparent cover and the capsule. The field of view of the objective optical system includes a spherical surface that is tangent to the transparent cover at a periphery of the field of view, and the near point of the depth of field on the optical axis of the objective optical system is positioned farther from the objective optical system than is the transparent cover. Various conditions are satisfied so as to provide high quality imaging.