This paper is composed of the following three steps. First of all, as a use characteristic of the car which uses a central district in Tama The use purpose facilities and the arrival interval of parking to each parking lot of time are totaled from the measurement data. This approximates to the function at parking time and arrival intervals. Next, these data and the capacity of the parking lot are used. The simulation to which the parking waiting time and the number of waiting are obtained in the time series is done. Finally, a proper scale of the parking lot corresponding to present demand is obtained by setting the upper bound at the parking waiting time corresponding to target facilities in the simulation. One methodology of the proper scale calculation of each step in the district where phased development like a central district in Tama is continued is presented from the above-mentioned result.