First circumferential grooves (first compressed air supply grooves, first pressure oil supply grooves, and a first coolant supply groove) formed on a first sliding surface, and second circumferential grooves (second compressed air supply grooves, second pressure oil supply grooves, and a second coolant supply groove) formed on a second sliding surface are formed in a rotary joint to be opposite to each other when seen from a radial direction of the rotary joint. In one pair of the opposite first circumferential groove and second circumferential groove, a type and a use of a fluid flowing in the first circumferential groove is the same as a type and a use of a fluid flowing in the second circumferential groove.