Water quality of the Kinokawa River has not been satisfied with the Japanese environmental quality standard. Then, origins of pollution of Kinokwa River were analyzed by L-Q equation and pollutant load per unit production using a field survey result and previous data. As a result, BOD and T-N values calculated from L-Q method were in good agreement with those calculated from pollutant load unit production method. The difference of T-P values between two methods was twice. Pollutant load source was estimated by pollutant load per unit production method. Main sources of BOD, T-N, and T-P in Kinokawa catchments were estimated to be domestic sewage, orchard, and industrial wastewater respectively. Comparing lower and upper stream of Kinokawa catchments, main sources of BOD and T-P in the upper stream were forest. Main sources of BOD and T-P in the lower stream were domestic sewage and industrial wastewater. Main sources of T-N in both streams were orchards. Therefore, each main source was various and comprehensive plan is necessary for controlling river water quality.