This study investigates the double dividend from an organic agricultural product label and looks at a real case to illustrate the influence an organic agricultural product label has on social welfare. Our model structure takes on two agricultural product suppliers that decide whether to adopt organic farming or not in order to obtain an organic agricultural product label. If the agricultural product supplier uses nitrogen fertilizer for farming, then it emits Nitrous Oxide (N2O), which is a greenhouse gas (GHG). At this time, the social planner decides to reduce the amount of N2O emissions in order to maximize social welfare. We conclude that the regulation of an organic agricultural product label can cut N2O emissions and promote consumer surplus. In other words, setting up an organic agricultural product label creates a double dividend effect. The Agricultural Research and Extension Station, Council of Agriculture, Executive Yuan is the main unit of research and development (R&D) in agricultural farming technology in Taiwan. By technology transfer and licensing, it can sufficiently help reduce a private firm's R&D cost in agricultural farming technology. Since there are two large-size rice suppliers in Taiwan, but only one supplier has its own organic paddy field and does organic farming technology R&D, social welfare in this area has room for improvement.