Casting method with improved resin core removal step

A casting method comprising the steps of:

• fabricating a resin core;
• setting the resin core in a die;
• subsequently charging molten metal into the die to form a cast product;
• subsequently taking out the cast product from the die by opening the die;
• and
• subsequently removing the resin core from the cast product, the resin of the core being of such a character as to maintain a mechanical strength satisfying a shape accuracy required for the cast product until solidification of molten metal in contact with the core and be softened when heated beyond the core temperature at which the molten metal in contact with the core was solidified;
• tentatively directly cooling the cast product containing the core down to near an ambient temperature;
• and
• re-heating the tentatively cooled cast product up to a predetermined temperature at which the resin core can be removed from the cast product without being broken apart by pulling one of its ends, the tentative cooling and the re-heating being executed after taking out the cast product from the die and before removing the resin core from the cast product.