This study was carried out to acquire the basic information of root growth under different pot size, imposing different space limitation on rhizosphere. Different size of pots that had same surface area but different depth, 5cm(Iength)$ imes$5cm(width)$ imes$30, 15, 5cm(depth), were used during the seedling stage of tobacco plant. Space limitation on rhizosphere affected not only the aerial growth, stem height, leaf area and shoot dry weight, but also root growth and root architecture. Aerial growth was highly related to growth of underground part, so space limitation on rhizosphere decreased aerial growth. Limitation on pot volume by reducing pot depth induced new rooting on crown. Root number and relative multiplication rate were higher in small pot that had 5cm depth than large pot, but total root length and mean extension rate showed reverse patterns. Root numbers of 1st order and 2nd order were increased as pot depth was increased, but the root number of 3rd order was increased in small pot. Root system of seedling grown in large pot distributed more horizontally than that in small pot at 20 days after temporary planting (DAT), but the root architecture of seedling was reversed at 25 DAT.