PURPOSE: To prevent deviation of a rotating body from a bearing body by providing guide grooves, extending in circumferential direction, on either one of the peripheral surfaces of the rotating body and bearing body opposed to each other to form uniform static pressure distribution over entire peripheral surfaces of the rotating body.

CONSTITUTION: A roughly cylindrical rotating body 2 is inserted into a bearing body 1 and a clearance C is formed between them. Multiple gas-inlet holes 3 are provided in the bearing body 1 at equally-spaced four positions in its section, and pressurized air is supplied to the holes. A pair of front and rear guide grooves 4, which are positioned at places opposed to the gas inlet holes 3, are formed around the periphery of the rotating body 2 in annular shape. Even if the rotating body 2 is deviated by some reason, a clearance of the bearing in radial direction is maintained at least that equal to the depth of the guide groove 4 at position C2 where the clearance is reduced to the minimum. Accordingly, the pressurized air from the gas-inlet holes 3 is distributed sufficiently to uniform static pressure distribution around the rotating body 2, thus returning the rotating body 2 from the deviated position to the center position.