The suicide rate in Korea has been declining steadily after peaking in 2011. However, to date, time-series analyses of Korean suicide rate data have mainly addressed factors related to increases in suicide rates. This study analyzed one of the most important evidence-based public health strategies to decrease suicide, that is, preventive effects of restricting access to lethal means via a charcoal-selling procedure improvement campaign, using multivariate time series analysis. The results showed the campaign in Gyeonggi Province had a significant effect on decreasing the number of charcoal-burning suicides in this area. It is believed that the present study has important implications in terms of providing the first empirical evidence for the charcoal-selling procedure improvement campaign in Korea. Further repeated research is needed to evaluate the impact of the intervention when the more enough observational data become available.