PURPOSE: To pressurize by delaying the solidification of a molten metal at the lower end part of a runner after pouring a molten metal and to manufacture a thin casting with good product yield by making the lower end part of the runner of a lost-wax pattern at higher m. p. than that of the foam pattern in case of casting a thin product with a full molding method.

CONSTITUTION: In the case of casting a thin casting with a full mold pressurizing casting method the lower end part 7c of the runner 7a of a polystyrene made lost-wax pattern 7 is cast by pressurizing it as the melting part 8 capable of melting at higher m. p. than that of the lost-wax pattern 7 and by the molten metal. At the lower end part 7c of the runner 7a it is composed of the partition part 8a arranged by partitioning a mold part 7b and runner part 7a and the outer peripheral part 8b winding the circumference thereof so as to wrap it. When a molten metal is filled from a sprue 10, it stagnates once at the runner part 7a and the progress of the molten metal to the mold part 7b is delayed, and meanwhile the pressurization of the molten metal is enabled and the full mold casting of a thin casting by the pressurized casting of the molten metal is enabled without any solidification of the molten metal immediately after its filling in the mold part 7b like a thin mold.