The degree of maturity of rice greatly affects the quality of the rice, including factors such as the integrity of grains, color, and the nutritive components. Green Rice$^{(R)}$ is rice (Oryza sativa L.) that has been harvested earlier than brown rice and appears green in color. To determine suitable harvesting time of the Jinbu variety of Green Rice$^{(R)}$ in Gyeonggido, rice samples harvested on 23, 26 and 42 days after heading (DAH) were compared on their yield, color intensity, and proximate compositions. The maximum paddy yield of Green Rice$^{(R)}$ was 61.4% at 23 DAH, which decreased to 45.4%, 5.5% at 26 and 42 DAH, respectively. Greenness was darker at 23 DAH ($-0.27{pm}0.03$), and significantly weaker (p<0.05) at 26 DAH ($0.07{pm}0.01$) and at 42 DAH ($5.25{pm}0.08$). All proximate compositions, except carbohydrate, including moisture, crude fat, protein, ash and total minerals were higher in the earlier-harvested Green rice$^{(R)}$ than in brown rice, without variations among the 23 and 26 DAH Green rice$^{(R)}$. Overall, the optimum harvest time of Jinbu Green Rice$^{(R)}$ at Gyeonggido would be 23 DAH. We suggest that timely harvesting could be a potent determinant of the quality of Green Rice$^{(R)}$.