To provide a thrust sliding bearing that can eliminate problems of a mounting space and an economical cost by decreasing a radial dimension by forming a radial sliding bearing part within upper and lower cases without using a radial sliding bearing.

The thrust sliding bearing 1 includes: a synthetic resin lower case 2; a synthetic resin upper case 3 stacked on the lower case 2; and a synthetic resin thrust sliding bearing piece 4 disposed between the upper case 3 and the lower case 2.