ROTARY JOINT

This rotary joint 1 has mechanical seal devices 7 each of which has: a first shaft-side sealing ring 71 and a second shaft-side sealing ring 72 which are attached to a shaft body 5; a first case-side sealing ring 73 and a second case-side sealing ring 74 which are attached to a case body 2. The first shaft-side sealing ring 71 and the second shaft-side sealing ring 72 have contact surfaces 71b, 72b that make contact while axially facing each other, and both the contact surfaces 71b, 72b have grooves 421c, 421d formed therein to constitute a second communication flow passage 42 that connects a second outer flow passage 32 and a second inner flow passage 62. 旋转接头(1)的各机械密封装置(7)具有：第一轴侧密封环(71)及第二轴侧密封环(72)，它们安装于轴体(5)；以及第一壳体侧密封环(73)及第二壳体侧密封环(74)，它们安装于壳体(2)。第一轴侧密封环(71)和第二轴侧密封环(72具有彼此在轴向上相对且接触的接触面(71b、72b)，在两个接触面(71b、72b)形成有用于构成将第二外侧流路(32)和第二内侧流路(62)连结的第二连通流路(42)的槽(421c、421d)。