PURPOSE: To provide a universal joint which is compact, having a long life and capable of transmitting high torque by providing a pair of boss parts positioned at an inner side of an outer peripheral surface of a flange part and a ring which is fitted to the peripheral surface to connect a pair of arm parts and of which an outer peripheral surface is at an inner side than a pair of flange parts.

CONSTITUTION: Annular grooves 27, 27 are dug in a surface on a side of a yoke 17 of a pair of flanges 25, 25, and a ring 28 is fitted to an outer peripheral surface of a pair of boss parts 19, 19 formed by these grooves 27, 27 so that an outer peripheral surface of the ring 28 can be positioned at an inner side than an outer peripheral surface 25a of the flange parts 25, 25. With this constitution, an outer diameter of the flange parts 25, 25, namely, that of a universal joint is prevented from increasing by a quantity of thickness of the ring 28. Consequently, this universal joint can be fitted for use to a rolling machine roll to which a conventional universal joint can not be fitted because of an excessive large diameter of the joint. Also, if a diameter of this universal joint is made the same as the conventional one, rigidity can be increased than conventional.