This study applied micro-nano bubble (MNB) technology to rice paddy soil and evaluated its effectiveness in reducing methane (CH₄) emissions. The experiment was conducted in a lysimeter plot at Meiji University's Ikuta Campus, using a treated plot supplied with MNB and a control plot constantly filled with water in 2022 and 2023, with an intermittently irrigated (AWD) plot in 2023 only. The results showed that in 2023, the MNB treatment plot reduced CH₄ emissions on the PVC pipe by 78.1% compared to the control plot, and by 75.5% at a distance of 50 cm, confirming the same level of emission reduction as the AWD plot; the MNB treatment plot was as effective as the AWD plot, with the effect of MNB treatment plot comparable to that of AWD, and the range of effectiveness of MNB was similar to that of AWD, depending on the variation of redox potentials in the soil. The effect of MNB application was comparable to that of AWD, and the effect range of MNB extended 15 cm upward and 50 cm horizontally due to changes in the redox potential in the soil, but the development of the rhizosphere also suggested that the effect range was limited. However, the results also suggest that there is a limit to the extent of the effect due to the development of the root zone. Further verification in actual paddy fields is needed.