<p>We have recently proposed a coprocessing method of heavy oils and a low-grade iron ore consisting of FeO(OH) in order to produce both light oil and a raw material for iron making called iron ore/carbon composite (IOC). In this study the effect of heavy oil type on a gasification reaction rate of the carbon in the IOC was investigated. It was shown that the carbon formed in the pore space of the low-grade iron ore was gasified at as low as 650°C due to low carbon crystallinity as well as a large contact area between the carbon and iron ore which can catalyze gasification reaction. While crystallinity and reactivity of the carbon formed in the pore space of the iron ore did not largely depend on heavy oil type, those of the carbon formed outside the pore space were different depending on the heavy oil type, which caused the dependency of gasification rate of IOC on heavy oil type.</p>