A thrust sliding bearing (1) includes an upper casing (3) having an annular surface (2); an annular 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 surface (4) opposed to the annular surface (2) of the upper casing (3); and an annular thrust sliding bearing piece (6) and an elastic ring (7) which are superposed on top of each other and are interposed between the annular surfaces (2) and (4).