PURPOSE: To realize casting management with smalle amount of entrainment of gas by dipping a die casting product in medium molten metal with low wettability and reactivity with die casting alloy and heat-controlled at a constant temperature, and taking it out after the lapse of a prescribed time.

CONSTITUTION: In a blister device A, heat insulting materials 2 are provided at the side circumferential plane and outside the bottom plane of a crucible 1 made of iron in closely contact shape, and also, a sheath heater 3 is wound and embedded in the side circumferential plane and the bottom plane wall part of the crucible 1. The medium molten wetal with low wetability and reactivity with the die casting alloy is heat-controlled at the constant temperature (holding temperature) in the crucible 1, and the die casting product C is dipped in the fusion hot water B, and the product is heated, then, it is taken out after the lapse of the prescribed time. Therefore, it is possible to realize the casting management by which the die casting product with small amount of entrainment of gas and high quality can be casted by the blister testing method.