A unit-type strain wave gearing (1; 20; 40) comprising: a rigid internally toothed gear ; a flexible externally toothed gear meshing with the internally toothed gear ; a wave generator that causes the flexible externally toothed gear to flex into a non-circular shape and partially mesh with the internally toothed gear ; a cylindrical unit housing to which a first gear is attached, the first gear being either one of the internally toothed gear and the externally toothed gear ; an output member to which a second gear is attached, the second gear being the other one of the internally toothed gear and the externally toothed gear ; and a sliding bearing (8, 9; 28, 29) that supports a fixed-side member (A) and a rotating-side member (B) so as to be capable of relative rotation, the fixed-side member (A) comprising the unit housing and the first gear, and the rotating-side member (B) comprising the output member and the second gear, the sliding bearing (8, 9; 28, 29) being provided with a fixed-side sliding bearing surface (8b, 9b; 28b, 29b) formed on the fixed-side member (A) and a rotating-side sliding bearing surface (8c, 9c; 28c, 29c) that is formed on the rotating-side member (B) and slidably contacts the fixed-side sliding bearing surface (8b, 9b; 28b, 29b); characterized in that the fixed-side sliding bearing surface (8b, 9b; 28b, 29b) is defined by a conic surface of which a center line is a center axis line of the unit housing ; and the rotating-side sliding bearing surface (8c, 9c; 28c, 29c) is defined by a conic surface oriented in reverse of the fixed-side sliding bearing surface (8b, 9b; 28b, 29b). a rigid internally toothed gear ; a flexible externally toothed gear meshing with the internally toothed gear ; a wave generator that causes the flexible externally toothed gear to flex into a non-circular shape and partially mesh with the internally toothed gear ; a cylindrical unit housing to which a first gear is attached, the first gear being either one of the internally toothed gear and the externally toothed gear ; an output member to which a second gear is attached, the second gear being the other one of the internally toothed gear and the externally toothed gear ; and a sliding bearing (8, 9; 28, 29) that supports a fixed-side member (A) and a rotating-side member (B) so as to be capable of relative rotation, the fixed-side member (A) comprising the unit housing and the first gear, and the rotating-side member (B) comprising the output member and the second gear, the sliding bearing (8, 9; 28, 29) being provided with a fixed-side sliding bearing surface (8b, 9b; 28b, 29b) formed on the fixed-side member (A) and a rotating-side sliding bearing surface (8c, 9c; 28c, 29c) that is formed on the rotating-side member (B) and slidably contacts the fixed-side sliding bearing surface (8b, 9b; 28b, 29b); characterized in that the fixed-side sliding bearing surface (8b, 9b; 28b, 29b) is defined by a conic surface of which a center line is a center axis line of the unit housing ; and the rotating-side sliding bearing surface (8c, 9c; 28c, 29c) is defined by a conic surface oriented in reverse of the fixed-side sliding bearing surface (8b, 9b; 28b, 29b). <EOS>