The first purpose of this paper is to clear the relation between the number of houses and the leveling-down of loads. And the second is to clear the leveling-down of loads in mixed-use buildings. To evaluation the leveling-down of loads, we defined "mean load factor" and "diversity factor". With using these factors, we shows the conclusions as follows : With the increase the number of houses, "mean load factor" grows. But, if the number of houses goes over 15〜20, its change comes small. And we found out the optimal ratio of the mixed-use buildings between houses and offices.
