Two types of superconducting magnets were installed in the beam interaction region of the KEKB accelerator. One was a QCS superconducting magnets for final focusing of the e^- and e⁺ beams, and the other was a huge superconducting solenoid for the particle detector, Belle. While the two magnets had completely different cold masses, two refrigerators of the same cooling power were used during the long-term 12-year operation for the KEKB physics experiment. This paper briefly describes these two cryogenic systems, and reports the operational problems and development of the cryogenic systems for SuperKEKB.