By using Kolmogorov-Smirnov test, difference between observed and estimated numbers of stems of diameter class by the theoretical distribution was examined. We could ascertain that Weibull distribution was good for fitness of diameter distributions in each plot, stratum, cluster and total of block respectively (Tables 4, 5 and 6). Furthermore for the purpose of estimating the diameter distribution of the block by using Weibull distribution, we have recognized from the results of x2 (Eq. 8) and modified Freese's x2-value (Eq. 9) that it is the best way to estimate the diameter distribution by Weibull in each topographical stratum of a block and sum up these to block. From the result mentioned above, we suggest that for estimating the stand composition by aerial photographs, especially for estimating number of stems of diameter class by Weibull distribution, the method of estimating diameter distribution of stratified stands by topography on aerial photographs will give the better result than diameter distribution estimated from the diameter and coefficient of variation interpreted on random or systematic points of aerial photographs.