A small-sized lightweight rotary joint for low-temperature application. A rotary joint for low-temperature application comprises: a housing (2); a non-rotation refrigerant pipe (3) provided within the housing (2) and having one end connected to the outside refrigerant source and the other end communicated with a portion to be cooled within a rotary machine; a rotatable rotation member (4) provided within the housing (2), having the refrigerant pipe (3) loosely inserted therethrough, and having one end affixed to the rotation section of the rotary machine; and a cylindrical relative rotation member (5) coaxial with both the refrigerant pipe (3) and the rotation member (4), having an affixed-side member (5a) affixed to the inner surface of the housing (2), and having a rotation-side member (5b) disposed so as to be rotatable inside the affixed-side member (5a). The affixed-side member (5a) is connected to the refrigerant pipe (3) through a refrigerant-pipe extension section (3a), and the rotation-side member (5b) is connected to the rotation member (4) through a rotation-member extension section (4a). The space (7) between the refrigerant pipe (3) and the rotation member (4) and the space (8) between the refrigerant-pipe extension section (3a) and the rotation-member extension section (4a) form a refrigerant region. A seal member (10) is provided between the affixed-side member (5a) and the rotation-side member (5b). A vacuum chamber and a pressure chamber are defined within the housing (2) by the peripheral wall of the refrigerant pipe (3), the refrigerant-pipe extension section (3a), and the affixed-side member (5a) of the relative rotation member (5).