PURPOSE: To improve thickness accuracy and to perform molding under low pressure by using a fabric wherein the thickness of a long base material is made larger than the mean thickness thereof in a specific ratio at a definite distance from both side end parts of the long base material and impregnating the same with a thermosetting resin to prepare a prepreg and laminating the respective prepregs.

CONSTITUTION: A fabric wherein the thickness of a long base material is made larger than the mean thickness thereof by 5 - 100% at a region of a definite distance of 0 - 100mm from both side end parts of the long base material is used in one layer or all of layers to be impregnated with a thermosetting resin to prepare a prepreg and the respective prepregs are laminated. When the thicknesses in the vicinity of both side end parts of the long fabric are made large, the thickness of yarn is increased at a part in the vicinity of the end parts. A plurality of the prepregs impregnated with the thermosetting resin are superposed one upon another or combined with usual prepregs to be superposed thereon and molded under heating and pressure. At this time, the molten resin flows out from the end parts of the base materials of the prepregs by molding pressure but, since the thicknesses of the end parts of the base material are large, the outflow of the resin from the end surfaces of the prepregs is suppressed to the min. degree.