A thrust sliding bearing reduces the number of components to thereby reduce the burden of assembly and components management and prevents unusual wear of a surface of an annular synthetic resin-made sliding bearing piece, which faces an annular metal plate. A thrust sliding bearing comprises an upper case which is integrally formed at least by an annular upper case base having an annular bottom surface and by an upper case cylindrical portion which is provided vertically from the annular bottom surface of the upper case base to be fitted in a lower case, wherein a synthetic resin-made sliding bearing piece is fixed to the inner side of the upper case cylindrical portion.