In the practice of sellecting élite trees. much attention should be paid to the slenderness of their crown. The degree of slenderness can be represented with the diameter of a crown in relation to the stem diameter at breast height. The formula for this relationship can be derived from the REINEKE's formula for the density of stands, namely: logS=K_s+0.803logD S: diameter of crown (m) D: diameter at breast height (cm) K_s: constant representing the degree of crown slenderness. This formula, however, has not been proved yet whether it applies or not to individual trees, because RETNEKE's original formula was introduced based on the observation of stands, but not of individuals. So the present author tried to examine the relationship with individual trees to check this formula. Each 40 trees, taken in a ca. 200-year old natural stand and a ca. 35-year old naturally reproduced stand of Pinus densiflora, respectively, were measured of their diameter of both crowns and stems at breast height. These two stands were situated on north-eastern slope (ca. 800-1000m. above sea level) of Mt. Kosikidake in the Kirisima volcanic area, Southern Kyusyu, separated by ca. one kilometer from each other. Results showed, that the above formula derived from REINEKE'S, can be applied to individual trees (figs. 2 and 3). The author proposes a numerical value, which could be named as “spacing value”, representing the degree of crown slenderness of individual trees. It is dencted as K′_s in the following formula, K′_s/100=logS-0.803(logD-1) Then, the spacing value of Pinus densiflora in the surveyed area shows the values of from ca. 20 to 48, 33.1 on average.