This study investigates a method to calculate nutrient emission factors using existing in formation based on mass balance in orchard and also evaluated the applicability and availability of the calculated emission factors in the Kinokawa River Watershed. The results showed that it was possible to calculate emission factors for applying for a pollution load and river water quality analysis. Moreover, the advantage of this method is that emission factors could be simply calculated using an amount of fertilizer. That is why the calculation method of emission factors examined in this study makes it easy to estimate the reduction of nutrient runoff based on managing the amount of fertilizer.