The performance of coke in blast furnace (BF) used to prefer a high strength and low reactivity, generally. One of the reasons is in the importance of the gas and liquid permeability in BF, which are related to the stable operation of BF. On the other hand, the energy saving on the BF will contribute the decrease of CO₂ emission, because the proportion of CO₂ emission in the iron making field is quite large. To decrease the reducing agent ratio the reaction efficiency in the BF should increase more and more. It is recognized that the reactivity and the strength of coke contradict each other. The high reactivity coke generally has a low strength. To overcome the contradiction, we are going to use the catalytic effect on the coke gasification. Therefore, it is important to clarify the mechanism of coke gasification concerning to the coke microstructure and porosity. In this study, the coke gasification were analyzed using μ-X-ray CT. The optimum conditions for the image processing of the data from the μ-X-ray CT were obtained through the comparison with the cross section of the coke embedded in the resin. Nondestructive observation became possible. It was found that the relatively larger structure (carbon and pore: ~0.5 mm) were almost the same between the μ-X-ray CT and the cross section of the sample embedded in resin, but smaller structure could not observed appropriately. The problems (ex.: existence of iron catalysts, difference of thickness for X-ray absorption, etc.) to get a proper image by μ-X-ray CT still remained.