This study was carried out to find out the effect of seeding rates and N upon the chemical composition and dry matter yield of lapanese barnyard millet (Echinochloa crusgalli var frumentacea (Roxb.) W.F. Wight). Two different seeding rates of Japanese barnyard millet (main plot) were 2 and 4㎏ per l0a and as subplot 5, 10 and 15 15㎏ per l0a of N was applied. The experiment was arranged as a split-plot design with three replications and undertaken over a period of 3 months from June to August, 1979. The results obtained are as follows: 1. DM yield was influenced by N fertilizer level There was no significant differences between forage yieles obtained from a single 10㎏/l0a of N application plots and 15㎏/l0a of N application plots while a significant differences at 5% level between 5㎏/l0a of N plots and other plots was shown. Therefore it is apparent that 10㎏/l0a of N level seems to be a desirable level when N fertilizer is used in a single application. 2. Seeding rates did not affect DM yield at any N level. There was no interaction between S (seeding rate) x N(nitrogen level) for DM yield. It was indicated that 2㎏ seeding rate per l0a was advisable in drilled plot. 3. Percent crude protein was greatly influenced by the different N fertilizer level. Crude protein yield showed high yield as N fertilizer increased and low as decreased. 4. Neither seeding rates nor N fertilizer levels had any effect on the plant height, and higher leaf-stem ratio in 15㎏/l0a treatment than that of other treatment was observed.