In general, when real estate gets old, its rental fee will decrease by 1 % every year.
However, there is difference of rate of decrease between new apartment and old apartment.
Rental fee of residential apartment is not affected by business condition.
But, rental fee will decrease when the apartment or individual house gets old.
（ But, even if once rental fee decrease, if owner renovates facility of the room, rental fee will increase again. ）
So, I will show you a result of investigation of apartments that are located in Tokyo 23 ward.
According to diagram above, there are 3 phases of decrease of rental fee.
The 1st phase is during 3 ～10 years from its completion.
When age of building is within these period, the building is still new and has to complete with newly built apartment.
So, rate of decrease is severe.
And the 2nd phase is during 11 ～ 20 years.
Compared to period mentioned above, rate of decrease is moderate.
Because, these apartments do not have to compete with newly built apartment.
The 3rd phase is after 20 years from its completion.
Rate of decrease of rental fee is slower than prior period.
Especially rate of decrease of rental fee of apartment for single person is almost zero.
Rate of decrease of rental fee is affected by other competitive buildings.
So, even if an apartment gets old, when there is not enough supply for specific area, rate of decrease of rental fee will be moderate.
In this diagram, apartments are classified into 2 categories.
Apartment for a single person : room area is from 18 ～ 30㎡
Apartment for small number of family. Room ares is from 30 ～ 60㎡.
In this investigation, apartments are located within 6 minutes from the nearest station, located in 4 th story. Accessible to center of Tokyo within 10 minutes by train.
(Quoted from Sumitomo Mitsui Trust Research Institute)