PURPOSE: To reduce the necessary force at the time of releasing a casting product having plural bore parts from plural fore cores by ejector pins.

CONSTITUTION: At the time of releasing the casting product 10 having plural bore parts 10-1, 10-2, 10-3, 10-4 from the bore cores 11, 12, 13, 14 by the ejector pins 17, the bore cores 12, 13 being the parts of plural bore cores 11, 12, 13, 14 are made to be movable to the mid-way of the moving range of the ejector pins 17, thereby the bore parts 10-1, 10-4 are precedingly released from the bore cores 11, 14 being the other parts of the plural bore cores 11, 12, 13, 14.