A thrust sliding bearing (1) includes an upper casing (3) which is made of polyacetal resin and has an annular lower surface (2); a lower casing (5) which is made of a reinforced synthetic resin including, in addition to polyacetal resin, reinforcing fibers such as glass fibers contained in this polyacetal resin, is superposed on the upper casing (3) so as to be rotatable about an axis O of the upper casing (3) in an R direction, 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 (6) which is made of polyacetal resin and is interposed between the annular lower surface (2) and the annular upper surface (4); and a tubular radial sliding bearing piece (7) made of polyacetal resin.