A method for manufacturing a flexible composite belt or cable, in the method, one or more parallel reinforced plastic profiles (11) are manufactured by pultrusion, continuous lamination or other continuous method. After surface treatment, the reinforced plastic profiles (11) are guided at a short distance from one another to coating treatment, which is carried out by extrusion or lamination or pultrusion. In the coating treatment, the reinforced plastic profiles are enveloped with a coating material (12) improving wear resistance which joins the reinforced plastic profiles (11) together and forms the coating of a finished belt or cable (10). Finally, the finished belt or cable (10) is wound on a reel.