We compared plant growth and nitrogen acquisition between nodulated (+nod) and non-nodulated (-nod) plants under low and high soil NO₃ conc. along light intensities in a N₂-fixing plant, Lotus japonicus. Except under the highest light condition (685μmol m^-2 sec^-1) and under 0.01mM NO₃ conc., growth of +nod was lower than that of -nod. The possible causes for the phenomena were different among soil nitrate concentrations. Under 0.01mM NO₃ conc., total nitrogen content per plant was higher in +nod compared to -nod regardless of light intensities and %Ndfa of +nod were above 70%. These results correspond to the general aspects that higher cost of carbon consumption belongs to N₂-fixation prevents biomass production of +nod. Under 1mM NO₃ conc., plant biomass, root biomass, plant nitrogen content and nitrate absorption were larger in -nod compare to that of +nod. Large proportion of nitrogen was acquired through nitrate absorption even in +nod. Plant nitrogen content par root biomass did not differ among +nod and -nod. Root biomass did not differ among soil NO₃ conc. in +nod. Suppression on root morphogenesis due to nodulation might prevent not only nitrate absorption but also biomass production in +nod under 1mM NO₃ conc.