A method of molding a shape of mascara brush bristles for eyelash makeup, the method comprising: - preparing a mascara brush having brush bristles and two strands of iron cores, where nylon bristles constituting brush bristles are put on the two strands of iron cores and twisting them spirally several times, so that the dorsal portions of the nylon bristles are formed radially on the basis of the iron cores; - putting the mascara brush in a mold, said mold having a lower mold, an upper mold and a guide posts, and where the lower mold has molding apertures with molding slots and where the upper mold has protrusions with molding slots; - seating said brush bristles of the prepared mascara brush into the mold in the molding apertures of the lower mold; - joining the upper mold to the lower mold by means of the guide posts; forming a dorsal potion molding hole, and hence, the dorsal portions of the brush bristles are formed: ∘ because the protrusions are inserted into the molding apertures forming applying dorsal portions; and ∘ being formed arranging dorsal portions by the molding slots (132 and 122); - putting the mold, in which the brush bristles are seated, into a molding furnace and heating the molding furnace so that the brush bristles of the mascara brush made of nylon are thermally transformed into a form corresponding to applying dorsal portions and arranging dorsal portions; - drawing out the mold and extracting the mascara brush having the dorsal portions 21 completely molded; and - annealing the mascara brush at room temperature. - preparing a mascara brush having brush bristles and two strands of iron cores, where nylon bristles constituting brush bristles are put on the two strands of iron cores and twisting them spirally several times, so that the dorsal portions of the nylon bristles are formed radially on the basis of the iron cores; - putting the mascara brush in a mold, said mold having a lower mold, an upper mold and a guide posts, and where the lower mold has molding apertures with molding slots and where the upper mold has protrusions with molding slots; - seating said brush bristles of the prepared mascara brush into the mold in the molding apertures of the lower mold; - joining the upper mold to the lower mold by means of the guide posts; forming a dorsal potion molding hole, and hence, the dorsal portions of the brush bristles are formed: ∘ because the protrusions are inserted into the molding apertures forming applying dorsal portions; and ∘ being formed arranging dorsal portions by the molding slots (132 and 122); ∘ because the protrusions are inserted into the molding apertures forming applying dorsal portions; and ∘ being formed arranging dorsal portions by the molding slots (132 and 122); - putting the mold, in which the brush bristles are seated, into a molding furnace and heating the molding furnace so that the brush bristles of the mascara brush made of nylon are thermally transformed into a form corresponding to applying dorsal portions and arranging dorsal portions; - drawing out the mold and extracting the mascara brush having the dorsal portions 21 completely molded; and - annealing the mascara brush at room temperature.