Fe2+/Fe3+ salt-containing cubic phases were prepared by hydrating the molten monoolein (MO)/stearic acid (SA) with the iron ions solution. Optically isotropic cubic phases and phase transition temperature of cubic phase having a series of different MO/SA ratio were obtained. Cubic phase nanoparticles (so-called cubosomes) containing iron oxide nanoparticles (IONs) were prepared. The saturation magnetization of cubosomal IONs was lower than that of IONs prepared in bulk phase. Iron ions chemically deteriorated MO of cubic phase 30days after stored at room temperature, indicating that ION-containing cubosomes should be prepared soon after iron ions-containing cubic phase is formed.