This research make the average frequency of renovation clear in the district where traditional townscapes are preserved, and identify the factors of restoration, that determine the frequency, in order to maintain a viable environment. Four conclusions are pointed out. 1) Remodeling of interior space are important. 2) Commercial facilities have been renovated more frequently than dwellings. 3) The frequency as a standard in one century are as follows : 1 or 2 times of facade restorations, 2 or 3 times of interior remodeling and once equipment remodeling or structural reinforcement. 4) Building size and site size are positively correlated to the frequency.
