PURPOSE: To facilitate removing of non-product part and to improve accuracy of a product by integrately arranging sand core having core print part in a metal pipe and inserting the metal pipe in a cam shaft forming part as cast-in.

CONSTITUTION: The metal pipe 11 having almost the equal length as the whole length of the cam shaft product is prepared and the sand core 12 having the core prints 12a, 12b projecting from both ends of the metal pipe 11 is arranged and integrated. The pipe 11 is arranged at the forming part 3 in the main mold 1, and the main molds 1, 2 are integrated under supporting condition of the core print parts 12a, 12b with molten metal introducing part 5. Next, the pipe 11 is inserted as the cast-in. Then, the non-product parts 15, 16 can be easily cut and the cam shaft product is obtd. Further, as the metal pipe 11 is inserted as the cast-in, centering accuracy of the hollowing part is improved and the product accuracy is improved.