A fuel-cell compressed-air supplying device 6 includes a centrifugal compressor 12 provided in a casing 11 and a bearing device 14 for supporting a rotation shaft 13 of the compressor 12. The bearing device 14 includes a pair of radial foil bearings 21 and 22 provided coaxially with the rotation shaft 13 for supporting the rotation shaft 13 in the radial direction, a pair of axial foil bearings 23 and 24 facing to the rotation shaft 13 in the axial direction for supporting the rotation shaft 13 in the axial direction, and a secondary bearing means 25 which is constituted by a combination of plural permanent magnets 61a, 61b, 62a, 62b, 63a, 63b, 64a and 64b and holds the rotation shaft 13 in a non-contact manner at static states.