To provide a step-up bearing simple in structure for obtaining boosted force and energized force because a turning force applied to an outer ring is output as boosted force to an inner ring and a means for it can be taken in the same shaft.

A bearing base is formed by interposing rotors in a mutually turnable manner between respective rings of a composite ring with a middle ring provided between the inner ring and the outer ring, and providing the upper face of the base with an annular band recess stepped down to arrange levers lined up around the center of the base. The inner ring and the outer ring are formed with corrugated sliding surfaces to which the levers are pressed, as the stepped-down surfaces of the annular band recess, and the corrugated pitch of the outer ring is formed wider than that of the inner ring. The levers are arranged such that one lever journaled to the middle ring by a check pin and joined to the sliding surface of the outer ring, or the other sub-lever interlocked with the one lever as the main lever, is joined to the sliding surface of the inner ring and that pressing force associated with corrugated shape, received from the sliding surface of the outer ring due to this lever arrangement presses the sliding surface of the inner ring through one or several levers to turn the crest parts of the corrugated shape progressively by the pressing force.