This experiment was carried out to investigate the optimum planting density in low fertilizing cultivation of machine transplanting in rice field of Honam Agricultural Research Institute, NICS for $2004{sim}2005$. Sobibyeo which belongs to medium maturing variety and Nampyeongbyeo which belongs to medium-late maturing variety were transplanted on May 30. In this experiment, there was no significant difference in heading date between planting density and nitrogen fertilization rate, and heading dates were August 8 in Sobibyeo, and August 14 in Nampyeongbyeo respectively. In relation to lodging character, lodging Index was high where the nitrogen fertilization rate and planting density were high. As planting density increases, panicle number per $m^{2}$ increased irrespective of nitrogen fertilization rate. When nitrogen was 6 kg/10a, rice yield of Sobibyeo was more where planting density was 90 hill per $3.3m^{2}$, and that of Nampyeongbyeo was more where planting density was 80 hill per $3.3m^{2}$. When nitrogen was 9 kg/10a, rice yield of Sobibyeo was more where planting density was 100 hill per $3.3m^{2}$, and that of Nampyeongbyeo was more where planting density was 110 hill per $3.3m^{2}$. Head rice rate of brown rice was higher when planting density increased, and was higher at 6 kg/10a nitrogen rate than 9 kg/10a nitrogen rate in all varieties.