together on a reel the modified epoxy resin is used when the heat resistance on the order of 130 u00b0 is required when the heat resistance as high as 240 u00b0 is required bismaleimide resin is used fig4 shows a formation of the strand and a covering process in which reference sign b designates a covering device a reel 40 having a composite element strand 381 manufactured in the previous process wound therearound is mounted on a supporting shaft 401 of the covering device b the covering device b is provided with a winding machine 45 around the movement path of the composite element strand and the fiber yarn 4 is wound around the winding machine 45 multifilament yarn formed of multipurpose fiber such as polyester fiber is suitable as the fiber yarn and for example that having 8 yarns of 1000 denier is exemplified the composite element strand 381 is wound by a strand reel 49 via a guide roll 42 and the winding machine 45 is turned around the composite element strand 381 in the course of movement to wind the fiber yarn 4 on an outer periphery of the composite element strand 381 to cover the outer periphery at an angle close to a.