The raindrop-size distribution (N_D distribution) is one of the most important meteorological factors because by using it we can obtain many other rain parameters. Recently Shiotsuki proposed the new method which determines the N_D distribution by using 10 minutes rainfall intensity data only. So the authors inspected this method by using the data of Western-Japan heavy rainfall, Nagasaki heavy rainfall, Ube, and seven locations in the Philippines. So the authors found the regional characteristics of a, b values included in Talbot type formula, which are the most basic in the Shiotsuki's method. And also found some ralationships between the values of a, b and N_D distribution.