To execute smooth injection by preventing the fixation of a plunger tip caused by the fusion of molten steel with a portion where the molten metal poured from a pouring hole drops without substantially damaging the heat retaining properties which a double-structure die casting sleeve possesses.

In the sleeve 10 for die casting constituted by metallurgically joining an inner cylinder 12 made of a tool steel having a thermal conductivity higher than that of an outer cylinder 11 with the outer cylinder 11 made of an alloy steel having the thermal conductivity of 10-25 W/(m.K) at 300°C, a notching portion 14 is arranged on the outer cylinder 11 at the portion where the molten metal 31 poured from the pouring hole 13 arranged in the sleeve 10 drops, and the thickness of the outer cylinder 11 in this portion is made thinner than the other portion of the outer cylinder 11 to enhance the heat radiation in this portion.