The reduction in human-induced emissions of CO₂ from automobiles, factories, power stations, etc., over the next 15 years is currently one of the most important issues facing the planet. We should therefore attempt to develop industrial processes using CO₂ as a feedstock in order to build a sustainable society in the near future. Photocatlaytic conversion of CO₂ has recently drawn increased attention due to allowing direct solar-to-chemical energy conversion. If H₂O does function as the electron donor, then it is important to obtain a stoichiometric ratio between the amount of O₂ evolved and the amount of CO₂ reduced. Moreover, the reduction of H⁺, released from H₂O molecules, usually competes with CO₂ reduction when several heterogeneous materials are used as photocatalysts for the reduction of CO₂ with H₂O. Generally, the production of H₂ via the reduction of H⁺ is the dominant pathway. Therefore, to achieve high selectivity in the photocatalytic conversion of CO₂ with H₂O, the electrons generated through the oxidation of H₂O must be controlled to selectively. Moreover, we achieved highly selective photocatalytic reduction of CO₂ by H₂O by simultaneously using an inhibitor of H₂ production and materials capable of CO₂ capture and storage, e.g., Ag-modified ZnGa₂O₄/Ga₂O₃, La₂Ti₂O₇, SrO/Ta₂O₅, ZnGa₂O₄, ZnTa₂O₆, Sr₂KTa₅O₁₅, SrNb₂O₆, LDH/Ga₂O₃, and Pr₂O₃/Ga₂O₃.