In order to examine the growth potency of excised roots varying in length, diameter and density in the culture medium, some experiments were tried on the view point of tissue culture. The results obtained were summarized as follows: 1. The elongation of isolated roots was better in the order of the class, A.B.C and D roots whose length were 8, 16, 24, 34 and 43 mm respectively. With regard to the growth within the same class, longer excised roots gave better result in compared with shorter ones. 2. The optimum number of root for the growth in liquid medium was found to be 5∼7 when the roots were used excised to the length of 10∼20mm. 3. The optimum root diameter for the growth of isolated roots was 0.42 mm at the base of root cap. On the other hand, the roots with larger diameter gave inferior effect.