To provide a foil bearing wherein the rigidity of a foil is adjustable in order to realize the stable rotation of a rotor in both low-speed/high-speed rotating areas, and the application of an excessive load to a part of the foil is avoided.

This foil bearing 23 has the foil 26 provided between the rotor 12 and a stationary retaining member 25. A rotatable movable member 27 is provided on the side separating from the rotor of the stationary retaining member, and a cam surface is provided on the surface of the movable member with which one end of a contact member 30 extended from the movable member toward the foil through a through-hole formed in the retaining member makes contact. The movable member is rotated to change the length protruded from the surface of the retaining member of the contact member, whereby the movable range of the foil is changed to substantially change the rigidity thereof.