The invention provides a golf ball having a core and one or more cover layer encasing the core, wherein at least one cover layer is formed by injection-molding a single resin composition of primarily (A) a thermoplastic polyurethane and (B) a polyisocyanate compound, and at least some polyisocyanate compound in which all the isocyanate groups on the molecule remain in an unreacted state is present in the resin composition. The golf ball has a high rebound, an excellent spin performance and an excellent scuff resistance, and the cover layer-forming resin composition has excellent flow properties and an excellent cover layer manufacturability.