In southern region of Korea, double cropping system including soybean as a second crop is widely adopted because prolonged high temperature in October enables soybean maturation even in late autumn. Global warming during decades derives transition of soybean planting dates as late as late-July. Delayed planting beyond the critical time moves reproductive stage to less favorable weather conditions like low temperature and short photoperiod, which can affect soybean yield and seed composition. Therefore selection of appropriate cultivar for changed climate and cultural practice is required. Effects of different eco-type and planting date on soybean yield was investigated for three sowing dates of 20 June, 5 July and 20 July with ten cultivars. Strong interaction between cultivar and sowing date was detected in number of branch, node and pod. No significant interaction was observed in 100-grain weight and yield, and this might be resulted from similar yield reduction pattern. Daepung, Taekwang and Uram recorded the highest yield when planted late, proving that these three cultivars are the most adaptable to delayed planting. Delayed planting results in higher sugar content, especially stachyose and raffinose which have detrimental effect on human health by causing flatulence and diarrhea. Protein content was decreased and oil content was increased in July 20 planting. Decrease in protein content was the largest in Hwangeumol and maintained high in Saedanbaek. This information will provide a guideline when select appropriate soybean cultivar in delayed planting to maintain yield and seed quality.