This study attempts to examine the average number of stored items of apartment residents composed of 4 family members and to compare the quantitative differences of the stored items according to the apartment size and the stage of life-cycle. The finding shows that the number of items stored in apartments increases as the size of apartments and the stag of life-cycle of husband and wife living in the apartments of more than 180$m^2$ increase approcimately twice, compared to those in the apartments of less than 83$m^2$. Therefore, the storage space in apartments should be designed more effectively considering the change of the stored items in relation to of the apartment size and their stage of life-cycle. This study suggests the specific design of the built-in closets for clothings, sheets, accessories and shoes based on the number of the items.