This experiment was carried out in order to study the plant growth and change. of nitrate-nitrogen content in the seedlings and ratoon crops of Japanese millet[Echiochloa crusgalli var frumentacea (Roxb.) Wight]. The resultes are as follws. 1. The maximum values of crop growth rate (CGR), relative growth rate (RGR), net assimalation rate (NAR), and leaf area ratio (IAR) occurred earlier than that of leaf area index (LAI) in the plots where seedlings were left to grow without cutting, however, when cuttings were practiced those were observed to appear almost simultaniously with that of leaf area inlet (LAI). 2. The maximum crop growth rate(CGR) of the seedlings appeared at the stage of stem elongation, while that of the ratoon crops occurred in 28 to 35 days after cut. 3. Leaf blade was higher in total nitrogen content but lower in nitrate-nitrogen than leaf sheath and stem. 4. Nitrate-nitrogen content was very high in the early growing stage of seedlings as well as ratoon crops, however, it gradually decreased with aging. Therefore the results of this experiment suggested that these would be a danger of nitrate poisoning to ruminants in case of feeding large amount of Japanese millet in early stage of growth.