The present invention provides a chlorine dioxide generation unit that can release practically sufficient amount of chlorine dioxide for an extended period of time while being compact. The present invention provides a chlorine dioxide generation unit, characterized in that said unit comprises an agent storage space portion and at least two light source portions, said light source portion is for generating light consisting of wavelengths substantially in the visible region, said agent storage space portion stores an agent comprising solid chlorite, and said agent storage space portion comprises one or more openings so that air could move in and out of said agent storage space portion, wherein chlorine dioxide gas is generated by irradiating said light generated from said light source portion onto said agent present inside said agent storage space portion.