To make a sufficient quantity of oil exist in a contact part, prevent the occurrence of metallic contact, and improve durability by arranging a recessed part capable of freely holding lubricating oil on an outer peripheral surface of the specific number of intermediate rollers among intermediate rollers.

Spiral grooves 49 and 49 are formed on an outer peripheral surface of a guide roller 32 and at least a single wedge roller 31a of a wedge roller being an intermediate roller, and these are formed as a recessed part capable of freely holding lubricating oil. The oil taken in the spiral grooves 49 is sent into respective inside diameter side contact parts 40 by centrifugal force on the basis of autorotating motion of the rollers even after an outside drum 11b slips out of oil gathered on the lower side of a housing 29a. Therefore, a sufficient quantity oil is made to always exist in the vicinity of a contact part of a first cylindrical surface 10a arranged on an outer peripheral surface of a central roller 9b and a third cylindrical surface 18a arranged on the outer peripheral surface of the guide roller 32 and the wedge roller 31a, and the occurrence of metallic contact can be prevented.