PURPOSE: To easily manufacture a metallic fitted member free from noise emission during operation by fitting the outside periphery of a shaft member made of ductile cast iron with an annular member made of carburized steel and applying austempering treatment to the above while keeping the above in the fitted state mentioned above.

CONSTITUTION: A shaft member 2, such as camshaft, is formed of ductile cast iron material. On the other hand, an annular member 3, such as drive gear, is formed of steel material to which carburizing treatment alone is previously applied. The outside periphery of a mating part 2a of the above shaft member 2 is fitted with the above annular member 3. Subsequently, austempering treatment is applied to the above while keeping the above-mentioned fitted state, by which the structure of the shaft member 2 is formed into a mixed structure of bainite and retained austenite and simultaneously hardening is applied to the carburized layer of the annular member 3. The coefficient of linear expansion of the ductile cast iron material with the above structure is higher than that of the steel material. Accordingly, in the resulting metallic fitted member 1, the widening of the clearance between the shaft member 2 and the annular member 3 due to high temp. can be prevented and also the emission of noises during operation can be prevented.