The effect of organic liquids (methanol+toluene, methanol+acetone and methanol+ ethylacetate) with the carburizing medium and nitrogen with a carrier gas on the internal oxidation of commercial carburized steels during carburizing in the atmosphere of cracked methanol gas were investigated. After water quenching, the outmost layer of carburized steel appeared uniform distribution of internal oxide at the grain boundaries and grain interiors. Below outmost layer the oxides formed at the grain boundaries. With increasing oxygen concentration in orgainc liquid and decreasing nitrogen addition to the carburizing atmosphere, the depth of internal oxide layer became thicker. It has also been found that the depth of internal oxidation increase with the silicon and manganes contents. It. was concluded that the control of the internal oxidation in drip- feed carbrizlng atmosphere is possible through lowering the CO gas content of the carburizing aimosphere with the addition of N₂ gas or by using the organic liquid having a superior cracking behavior (with smaller oyxgen radials) as a carburizing medium.