Kumamoto's 2025 population is now estimated at 735,149. In 1950, the population of Kumamoto was 195,000. Kumamoto experienced a decrease of -1,630 residents over the past year, marking an annual decline of -0.22%.These population estimates and projections come from the latest revision of the UN World Urbanization Prospects. These estimates represent the Urban agglomeration of Kumamoto, which typically includes Kumamoto's population in addition to adjacent suburban areas.