Monodisperse SiO2 particles of nanometer dimensions were fabricated by membrane emulsification using ideally ordered anodic porous alumina. For the preparation of monodisperse emulsion droplets, the dispersed phase was pressed through a porous alumina membrane into the continuous phase. After solidification treatment of the emulsion droplets, prepared spherical SiO2 nanoparticles with uniform sizes were obtained. From scanning electron microscope observation of the obtained particles, it was confirmed that the size distribution of SiO2 nanoparticles is relatively narrow.