PURPOSE: A high-vacuum die casting method is provided to effectively discharge gas inside a cavity for molding a metal product while molten steel is injected into the cavity. CONSTITUTION: A high-vacuum die casting method includes the following steps of: forming a cavity by adhering a movable mold (20) to a fixed mold (10); injecting molten steel inside a sleeve (30) via a molten steel inlet; moving a plunger inside the sleeve; vacuum-sucking and discharging gas inside the cavity to the outside via a first passage; vacuum-sucking and discharging gas inside a closed space to the outside via a second passage different from the first passage; and separating a metal product from the movable mold with an eject pin (50) by separating the movable mold from the fixed mold and moving an eject plate (40) toward the movable mold.
