This study aimed to estimate the methane emission from forest and cropland vegetation region by using WDCGG data, methane concentration, wind direction, wind speed, relative humidity and air temperature, from 1998 to 2007 on Minamitorishima, Yonagunijima and Ryori. We developed Greenhouse gas Emission Presumption Method (GEP Method) for presuming the methane concentration generated at the observation station. And this method was applied. As a result, The methane concentration was high in winter and low in summer on three sites. There was no difference of the methane concentration though day among morning, afternoon and nighttime. Annual average concentration in methane generation was 1820 ppb in onagunijima and 18 ppb was from sugarcane field. On the other hand, the annual average concentration was 1854 ppb in Ryori and 24 ppb was from forest vegetation region. Moreover, it was clarified that 70~80 percent of the amount of the methane emission was generated from vegetation region of forest and sugarcane field at the observation.