To restrain the displacement of a core during casting at the time of manufacturing a hollow blade under applying a lost wax method using the core.

A wax pattern 12 composed of the core 10 and a wax layer 11 covering the core 10 is manufactured, and successively, at least one of pin 18 having the same material kind as the blade, is inserted into the wax layer 11 and this pin 18 is abutted on the core 10. Further, a part of the pin 18 is projected from the outer surface of the wax layer 11 and thereafter, the dewax is executed under condition of holding the projecting part 24 of the pin 18 from the outer surface of the wax layer 11, and successively, the casting is executed.