PURPOSE: To improve bending strength, compressive strength, etc., and to allow the formation of the bat to a small thickness by molding an outside shell intensifying layer of a material which can form a specific crosslinked resin with continuous fibers as reinforcing fibers by a resin injection method.

CONSTITUTION: The outside shell intensifying layer is formed of monomers and prepolymers which can form a crosslinked polyamide resin, crosslinked epoxy modified polyamino amide resin or crosslinked polyester amide resin with the continuous fibers as the reinforcing fibers. The bat is integrally molded by the resin injection molding method which brings such monomers or prepolymers into reaction curing in metallic molds. A two-liquid injection machine is used as an injection device for the materials which can form the crosslinked resins. Namely, a core material 2 having an approximate bat shape is formed of the meltable materials. A sleeve and mat roving consisting of the reinforcing fibers 3 are coated and wound to form a molding 5. This molding is disposed in the molds 4 for molding the bat and the molds are compresses to reduce the pressure in the molds; thereafter, the crosslinked resin raw materials are injected from the two-liquid injection machine through the injection port 6 and are brought into reaction curing.