Hierarchical nanoporous structures were fabricated from mesoporous silica and organic monolith with the aim of fabricating a high-efficiency catalyst carrier. The hierarchical structures were modified with photocatalytic titanium clusters. The hierarchical structures showed higher photodecomposition rate of isopropyl alcohol than mesoporous silica structures or monolith structure did, even though the surface area of the hierarchical structure was the smallest. In addition, the CH4 generation from CO2 photoreduction on the hierarchical mesoporous structure was also confirmed. These results suggest the possibilities of highly efficient mass-transport property and the ease of chemical modification of our hierarchical structure.