The formation processes of the integrated ordered mesostructure of silica at the liquid-liquid interface in laurylamine/tetraethoxysilane system were elucidated by measuring the small-angle X-ray scattering pattern every second during the formation processes using strong synchrotron radiation X-rays. Cylinders of silica were formed in random configurations in the very early stage of reactions at the liquid-liquid interface. Since these cylinders were restricted in a two-dimensional liquid-liquid interface, they aligned easily with each other and made an ordered structure composed of aligned cylinders at the interface. These ordered structures then accumulated with each other, making an integrated ordered structure, such as a hexagonal array.