The electrical characteristics of the SiC MOSFET have been limited by large amount of states at the SiO2/SiC interface. In this study, the accuracy of the energy level of the interface states extracted by hypothetical high frequency extreme, which is conventionally used, is experimentally examined. It is demonstrated that conductance method at 65K enables us more accurate evaluation of the interface states at the SiO2/SiC interface and found that the interface states density (Dit) of nitride SiO2/SiC interface is over 1013 cm-2eV-1 at energy level of 0.1 eV below the conduction band edge.