Abstract: A resin-made belt pulley (p) including a rim (2) over which a belt is engaged and a web (3) molded together with the rim and mounted on a rotating shaft, (1) extending through a position radially inside of the pulley, characterized in that a mounting position (30) of the web (2) on the rotating shaft (1) is offset (12) from the center (8) of the rim (2) in an axial direction, and the web (3) includes a vertical web portion (7) extending from the mounting position (30) of the web in a radially outward direction of the rotating shaft (1) and inclined web portions (9) diagonally connecting the vertical web portion (7) to the center (8) of the rim in the axial direction. Since a belt tension acting on the rim (2) is born at the center position (8) of the rim (2), deformation of the rim (2) caused by the belt tension can be minimized even if the pulley (p) is fabricated from resin which is a material of low rigidity.