To shape at low pressure by preventing the surface of the shaped article from becoming rough because: crosslinker does not boil when shaping the shaped article while heating and pressing the same at shaping temperature of the shaping machining while pressing and heating of 135 to 160°C using a SMC (sheet molding compound); and the boiling point of a styrene monomer is about 149°C because vinyl ester resin is used as main agent and styrene monomer is not used as the crosslinker and the crosslinker with higher boiling point than the styrene monomer is used.

The resin composition is heated at heating temperature ranging from 65°C to 85°C and mixed, and the mixture is cooled, thereby forming the resin composition which is in a semi-solid condition at room temperature and becomes flowable condition at the heating temperature ranging from 65°C to 85°C. Thereafter the resin composition in the semi-solid condition is heated to the heating temperature ranging from 65°C to 85°C, a fiber base material 2 is impregnated with the resin composition in the flowable condition and cooled and shaped into a prepreg shape.