PURPOSE: To provide a die cast production method for an impeller housing where the impeller housing in which the resistance of the water flow from the suction side to the discharge side is small, and the fluctuation in the water pressure is hardly generated when the impeller housing is incorporated in a water jet pump.

CONSTITUTION: In a die cast method of an impeller housing 1, the mutual draft surface which is diagonally crossed relative to the radial surface passing through the axis of the impeller housing 1 is provided as the mutual mating surface ranging from the outer circumferential surface of a boss of the impeller housing 1 to the inner circumferential surface of the housing body 1a, and the impeller housing is manufactured by using the suction side trimming die and the discharge side trimming die where the outer and inner circumferential surfaces are smoothly continuous by setting the angle of inclination of this draft surface to be large.