In order to find out beneficial plant density and seeding date of non-/few branching soybean experiment was done with three seed densities 3 and 6 levels in 2006 and 2007, respectively. The results were classified into 3 categories. Firstly, increased seed density in May seeding increased culm length 7, 6 and 8 cm in Taekwangkong, Shinpaldalkong and Jilim21, respectively. In addition, high seeding density in May seeding decreased number of branches by 1.5, 1.2 and 1.2 in Taekwangkong, Shinpaldalkong and Jilim21, respectively, however, number of pods on main branch greatly decreased by 25, 24 and 16 in 1st year experiment. Secondly, seed yield 77 (g m-2) in Shinpaldalkong increased in 1st year experiment with increase plant density by increased pod numbers and 100-seed weight. Seed yield was highest (419 g m-2) in Sinpaldalkong 2 under 30x15 cm seeding distance sown at the middle of June. However, seed yield mostly increased with increasing seeding density in delayed seeding time in non-/few branching soy cultivars. In conclusion, increased plant density by 60x7.5 (cm) in mean of both year experiments increased culm length(cm) by 14, 12 and 10 cm Taekwangkong, Shinpaldalkong and Jilim21, respectively. However, seed yield 419 and 400 (g m-2) was highest in 30x15 and 30x10 cm, respectively in Shinpaldalkong in June seeding treatment but there was no yield increasing in other cultivars and seeding density, therefore double cropping system with non-/few branching soybean cultivar might be possible under effective seed density in the southern part of Suwon in South Korea.