To develope the model for measuring the total nitrogen contents in fresh leaf, the change of nitrogen content in fresh leaf was investigated under different nitrogen levels in japonica rice (cv. Nampyeungbyeo). The total nitrogen contents in fresh leaf showed a reduced trend reaching to matured growth stages, but increased after the nitrogen application at panicle stage. The total nitrogen contents were gradually augmented with increment of the planting spacing or the nitrogen levels at transplanting and panicle stage. The total nitrogen contents also showed a significantly year variation according to the nitrogen levels, planting spacing, nitrogen levels at panicle stage. The index of nitrogen nutrition in fresh leaf was increased reaching to matured growth stages, but decreased at panicle and heading stage. This result could be applied for fertilization diagnosis and prescription in the field.