A capsule endoscope is disclosed that includes first and second objective optical systems for forming images of objects viewed in the capsule insertion direction and in the opposite direction on separate areas of one plane where an image pickup surface of an image pickup device is located. The capsule endoscope also includes illuminators for illuminating the objects, and a deflector or deflectors, such as reflecting prisms, for folding light from the objective optical systems to the image pickup surface so that the image pickup surface is parallel to the capsule insertion direction. The objective optical systems are retrofocus optical systems. The illuminators may have emission surfaces centered on the centers of spheres defined by dome-shaped transparent covers aligned along a central axis of the capsule endoscope. The objective optical systems, the deflector or deflectors, and the image pickup device are arranged completely off the central axis of the capsule endoscope.
