PURPOSE: To suppress the heat loss in an exhaust port and prevant reduction of exhaust gas temperature and improve thermal efficiency of an engine by forming the adiabatic part by enclosing the periphery of the exhaust port with casted adiabatic members.

CONSTITUTION: The heat insulating core 10 which consists of the heat insulating member which has a plurality of penetrating holes 7, projection part 8 for preventing floating-up, and the vent hole 9 formed on the projetion part is attached onto the partition wall plate 6 which consists of the heat insulating metal plates equipped with the upwardly bent peripheral edge area 5 in manufacture, thus forming an adiabatic part forming member 4. The formed member 4 is installed, having a partition wall member 6 in contact with the core 3 for exhaust port, thus a casting mold 11 is constituted. Fused metal is injected into the space part 1 of the casting mold 11, and thus the cylinder head 14 which is equipped with the partition wall plate 6 of which peripheral edge area 5 is immersed into a case member and of which bottom surface is exposed to an exhaust port 16 and the adiabatic part 17 which consists of the adiabatic member 19 which contacts with the partition wall plate 16 and is equipped with a plurality of stays 18.