To provide a structure of a die for die casting machine excellent in the heat retaining property of molten metal and also, the strength and the ductility and having the long service life.

A fixed die 1 is fitted to the front surface of a fixed plate 2. A movable die 7 faced to the fixed die 1 is disposed and fitted to the front surface of a movable plate 8, and on this front surface, a cavity 9 is formed. A JIS-SKD 61-made die sleeve 3 is inserted so as to penetrate the fixed die 1 from the rear surface to the front surface. A heat insulating layer 5 made of a precipitation hardening series stainless steel (IS-SUS 630) is arranged between the die sleeve 3 and the fixed die 1 body. A plunger sleeve 4 made of the same JIS-SKD 61 is inserted so as to penetrate the fixed plate 2 for the rear surface to the front surface. The rear end of the die sleeve 3 is connected with the front end of the plunger sleeve 4. In this case the thermal conductivity at 300°C of the heat insulating layer 5 is 10-25 W/m.K.