To cut out a hard-brittle substrate by blasting, laying out substrates 2 on a plate material 1 made of a hard-brittle material with leaving a space for blasting; forming first protective films 4 on both surfaces of the plate material 1 at layout positions of the substrates 2; and forming second protective films 5 on both surfaces of a margin 3 of the plate material 1 with leaving a space with respect to the first protective films 4 and having outer edges from a periphery of the plate material 1 at a width of 5 mm or less; cutting regions 6 between the films 4, 4 and between the films 4, 5 from one surface of the plate material 1 to a depth of approximately half of a thickness thereof by blasting, then cutting from the other surface of the plate material 1 until the plate material 1 is penetrated.