A rotary joint for maintaining a cryogenic supplying refrigerant comprises a vacuum use cylindrical shaft supported in rotatable condition, a rotary seal ring fitted to an outer circumferential face with a space, a stationary seal ring provided at both sides of the respective rotary seal rings, a resilient bellows to press the stationary ring resiliently to the rotary seal ring side, a spaced fluid passage formed between the respective resilient bellows, a second fluid passage communicating with the spaced fluid passage, a connecting fluid passage communicating with the second fluid passage, a first pipe communicating through the spaced fluid passage, a connecting cover having a suction bore for vacuumizing and a magnetic fluid seal device having a projection constituted as multiple gaps corresponding to a pressure of the vacuumizing.