To investigate the root system of vigorous 6th years old fig tree on the sand dune, roots of the fig tree were digged and grouped together by the method as follows ; the Root zone was devided hbrizontally around the stem by 5 concentric circles of which radii were 1, 2, 3, 4, and 5 m, and vertically by the depth of 30, 60, 100, and 150cm from the surface of the ground. Then digged roots of each block were classified into 6 parts of root stem special large roots (Dia. over 20 mm), large roots (10-20 mm), middle roots (5-10 mm), small roots (2-5 mm) and fibrous roots (under 2 mm).
1. The raw root weight % of each class to all roots was as follows ; root stem : 9.14, special large roots : 15.63, large roots : 11.89, middle roots : 15.96, small roots : 16.47, fibrous roots : 31.78.
2. Roots more than 67 % distributed horizontally within 2 m-radius and roots to 30 cm in depth were about 61 %: and roots to 60 cm in depth were about 95%.
3. Fibrous roots extended horizontally more than 5 m from the tree and 58.6 % roots of them gathered within the limit of 0 to 60 cm in depth.
4. Top to root ratio of the fig tree was 0.87.