A resin pulley includes: an outer cylindrical portion having an outer circumferential surface on which a belt is to be wound; an inner cylindrical portion which is disposed radially inwards of and concentrically with the outer cylindrical portion; and a plurality of ribs connecting an inner circumferential surface of the outer cylindrical portion and an outer circumferential surface of the inner cylindrical portion. The outer cylindrical portion, the inner cylindrical portion and the ribs are formed integrally from a resin material, and the ribs are provided in such a manner as to be inclined towards a circumferential direction relative to a radial imaginary line as viewed in an axial direction.