Sliding bearing

A sliding bearing (1) includes an upper casing (3) having an annular lower surface (2); a lower casing (5) which is superposed on the upper casing (3) so as to be rotatable about an axis O of the upper casing (3) and has an annular upper surface (4) opposed to the annular lower surface (2) of the upper casing (3); an annular thrust sliding bearing piece (7) disposed in an annular space (6) between the annular lower surface (2) and the annular upper surface (4); seal means (8) disposed on an outer peripheral side of the annular space (6); and seal means (8) disposed on an inner peripheral side of the annular space (6).