Provided is a relay lens including a plurality of relay optical systems that are arranged in a long, rigid tube along a longitudinal direction and that re-form an image, wherein each of the relay optical systems includes a pair of rod lenses that are disposed with a space therebetween in the longitudinal direction, a barrel that is disposed between the pair of rod lenses along the longitudinal direction, and a positive lens that is fixed to an inner side of the barrel and that has a positive refractive power; and a length of the barrel in the longitudinal direction is larger than a thickness of a peripheral edge of the positive lens in the longitudinal direction.