Chlorine dioxide (ClO) can be used as an alternative disinfectant for controlling fungal contamination during postharvest storage. In this study, we tested the and inhibitory effects of gaseous ClO against SP-d1, the causal agent of sweetpotato dry rot. In tests, spore suspensions of SP-d1 spread on acidified potato dextrose agar were treated with various ClO concentrations (1-20 ppm) for 0-60 min. Fungal growth was significantly inhibited at 1 ppm of ClO treatment for 30 min, and completely inhibited at 20 ppm. In tests, spore suspensions were drop-inoculated onto sweetpotato slices, followed by ClO treatment with different concentrations and durations. Lesion diameters were not significantly different between the tested ClO concentrations; however, lesion diameters significantly decreased upon increasing the exposure time. Similarly, fungal populations decreased at the tested ClO concentrations over time. However, the sliced tissue itself hardened after 60-min ClO treatments, especially at 20 ppm of ClO. When sweetpotato roots were dip-inoculated in spore suspensions for 10 min prior to treatment with 20 and 40 ppm of ClO for 0-60 min, fungal populations decreased with increasing ClO concentrations. Taken together, these results showed that gaseous ClO could significantly inhibit growth and dry rot development in sweetpotato. Overall, gaseous ClO could be used to control this fungal disease during the postharvest storage of sweetpotato.