PURPOSE: To prevent the generation of soot, by coating the surface of a combustion chamber with ceramic and sticking an oxidizing catalyst on the surface of the ceramic to utilize the heat-insulating property of the ceramic to keep the temperature of the surface of the catalyst so high that the reaction of the catalyst is activated.

CONSTITUTION: A ceramic and catalyst area A is provided on the surfaces of main and auxiliary chambers 2, 3 of a cylinder head 1, the bottom of an exhaust valve 4, the top of a piston 5, etc. To manufacture the area A, the surface of a metal on which previous treatment is effected is heated so that powder of ceramic which contains zirconia as the main constituent and has a relatively large coefficient of expansion is melt-sprayed on the surface of the metal and the surface is thereafter coated with ceramic containing alumina as the main constituent. After that, the metal surface is further coated with a catalyst. The alumina layer on the metal surface is porous and has a large surface area so that the layer holds the catalyst well and sufficiently intercepts heat from the metal. For that reason, the purpose is attained.