The present invention aims at providing a technique for providing a stepped structure separately to a rotating shaft in a later step of assembly for preventing oil leakage from a bearing box. To this end, the rotating machine of the present invention includes a rotating shaft having a rotating member, a bearing device including a rotating shaft insertion hole larger in diameter than the rotating shaft, an oil thrower provided between an outer circumferential portion of the rotating shaft insertion hole and the rotating shaft, and an additional ring attached to the rotating shaft between the oil thrower and the rotating shaft such as to protrude in a radial direction of the rotating shaft.