In the upper reaches of the Yoshida River where the nitrogen concentration in headwaters was high, the distribution of nitrogen and major ions were clarified. About 70% of total nitrogen was NO3--N. NO3--N was the highest concentration of 2.1mg/l in headwaters. Its concentrations in the down stream in the investigation area were about 1mg/l. The major ion concentrations showed the reverse tendency with NO3--N. NO3--N was higher, as the forest rate in the catchment was higher. This result shows that in the upper reaches of the Yoshida River, the nitrogen load from the forest had a greater impact on nitrogen concentration of the river.