A roll outer layer material having remarkably improved wear resistance and a composite roll for rolling are provided. It is a gradient composition in which the W content decreases from the outer circumferential side toward the inner circumferential side in the radial direction, and at the surface of the outer layer material at a position corresponding to the maximum diameter when rolling is used, in mass%, W: 25 to 70%, Co: 5 to 45 %, and further contains C: 0.6 to 3.5%, Si: 0.05 to 3%, Mn: 0.05 to 3%, Mo: 1 to 15%, and the balance is a W-Co-based alloy composed of unavoidable impurities It is a roll outer layer material having a composition. It is preferable that the roll outer layer material is made of a centrifugal casting agent.