Provided is a chlorine dioxide generation device, suitable for long-term storage, discharging a chlorine dioxide-generating mixture that remains at an object of interest when used to thereby stably exhibit the effect of chlorine dioxide. A chlorine dioxide generation device, comprising: a first container containing a first composition comprising a chlorite and fumed silica; a second container containing a second composition comprising an acidic substance and fumed silica; an outer container housing the first container and the second container; a mixing section that mixes the first composition released from the first container and the second composition released from the second container to produce a mixed composition; and a discharging section that discharges the mixed composition produced by mixing in the mixing section.