PURPOSE: To provide a shaft which is lessened in unequal thickness and has rigidity uniform in the circumferential direction by winding reinforcing fibers impregnated with a thermosetting resin around a mandrel, setting this mandrel in metal molds and curing the resin by heating while jetting compressed fluid.

CONSTITUTION: The reinforcing fibers 4 impregnated with 20 to 30wt.% thermosetting resin are wound around the mandrel 1 after the hollow mandrel 1 having air injection holes 11 has been provided with a release layer 2. The mandrel wound with the reinforcing fibers 4 is set into the metal molds 3 for shaft molding and thereafter, air (compressed fluid) is supplied from the hollow part of the mandrel 1 and while the internal load is loaded on the mandrel by jetting air from the air injection holes 11, the resin is molded by heating. The release layer 2 expands according to the injection of the compressed fluid and the internal pressure is applied on the reinforcing fiber layer 4. After the reinforcing fiber layer is cured, the mandrel is removed and the production of the shaft ends.