The demand of high power Continuous Conduction Mode (CCM) Power Factor Correction (PFC) converter installed in charging devices for Electric and Hybrid Vehicles has grown in the recent years. In these converters, the inductor often appears as the largest component, consequently, the CCM boost PFC converter using coupled inductors is well-known as one of the topologies that can achieve miniaturization and weight reduction of the inductors. However, the change of the magnetic flux during a half cycle of the input AC voltage has not yet been analyzed in detail. Therefore, the cause of the difference of the magnetic saturation is not known. In the case of non-coupled inductor, the magnetic saturation occurs at a point of the peak inductor current. In contrast, in the case of the coupled inductor, the magnetic saturation occurs at a different point than the inductor current peak. In this paper, the change of the magnetic flux in a half cycle of the input AC voltage is analyzed. Additionally, the novel design method of the coupled inductor considering the maximum magnetic flux is proposed. Finally, the validity of the novel design method is confirmed by experimental tests.