To smoothly rotate a shaft even if the shaft is displaced in the radial direction or the axial direction for one shaft retaining a plurality of butterfly valves in parallel.

This bearing device includes a plurality of bearing structures 9 provided in a quadruple valve device 1 and rotatably supporting the shaft 4 for the one shaft 4 retaining four butterfly valves 6 in parallel. Each bearing structure 9 includes a rotating section 21 provided rotatably integrally with the shaft 4, a fixed bearing 22 provided around the rotating section 21, and a rotating bearing 23 provided between the rotating section 21 and the fixed bearing 22. A portion between the rotating section 21 and the rotating bearing 23 and a portion between the fixed bearing 22 and the rotating bearing 23 are respectively configured to be rotatable in any direction. At least one of the portion between the rotating section 21 and the rotating bearing 23 and the portion between the fixed bearing 22 and the rotating bearing 23 is configured to be slidable in the axial direction of the shaft 4.