the groove becomes like a ridge is formed between the irradiation areas before and after moving the axis therefore in order to make the bottom surface of the groove flat the axial lap ratio should be more than or equal to 20 note that when the carbon portion 4 covering the groove surface 2 a is buried in the groove 2 the ridge of the groove surface 2 a of the groove 2 enables to increase the contact area of the groove surface with the carbon portion 4 therefore it is possible to make the groove surface 2 a protrude by forming the groove surface 2 a under the irradiation condition of the axial lap ratio less than 20 to increase the adhesion of the carbon portion 4 with the groove surface 2 a according to the casting die of the present embodiment described above the carbon films coated on the movable die 1 and the stationary die become hard to peel because the carbon film becomes the carbon portion 4 buried in the groove 2 having the opening width of 45 u03bcm or less and the depth of 60 u03bcm or more additionally the carbon portion 4 buried in the groove 2 works as a heat insulating portion having high heat insulation and at the same time prevents the molten metal 11 from entering the groove 2 as described above according to the movable die 1 and the stationary.