To absorb an accumulated error and impact at the time of assembling a swivel joint.

A swivel joint has a joint outer 10 and a joint inner 21 fitted free to rotate, a fluid passage group formed on the joint outer 10 and the joint inner 21 and connected to each other, a lower side port forming member 38 fitted on a lower end part of the joint inner 21 free to rotate and on which a flange part 41 faces against a lower end surface of the joint outer 10, a fastening member 44 fastening the lower side port forming member 38 on the joint outer 10 as a male screw part is inserted into an insertion hole 42 opened on the flange part 41 and screwed in a screw hole 43 of the joint outer 10, a seal ring 50 sandwiched between opposed surfaces of the joint outer 10 and the flange part 41 and a seal ring 49 sandwiched between the insertion hole 42 and the fastening member 44. Consequently, it is possible to absorb an accumulated error and impact by the seal rings.