To provide a rotating speed difference sensing type joint capable to transmitting rotating torque even in a region where biaxial relative rotating speed difference is small.

A main body 14A of a check valve 14 is provided in a sliding hole 2g free to slide. The main body 14A is energized to the side of a cylinder hole 2b by a first spring 21, and the main body 14A is made to hit on a bottom surface of the sliding hole 2g until working oil in the cylinder hole 2b reaches specified initial pressure. An orifice 2j is opened on an inner peripheral surface of the sliding hole 2g. A through hole 14c is formed in a valve hole 14a of the main body 14A. This through hole 14c is arranged so as to be separated from the orifice 2j at the time when the main body 14A hits on the bottom surface of the sliding hole 2g and to be communicated to it facing against the orifice 2j at the time when pressure in the cylinder hole 2b exceeds initial pressure and the main body 14A moves to a specified opening position by working oil against the first spring 21.