Japan's child population under 15 was estimated at 13.29 million as of April 1, 2026, down 350,000 from the previous year, marking the 45th straight year of decline in numbers [1]. This figure is the lowest since comparable data collection began in 1950 [1].
Boys accounted for 6.81 million of the child population, while girls numbered 6.48 million as of the same date [1]. Children under 15 made up 10.8% of Japan's total population, a decrease of 0.3 percentage points from the year before. This marks the 52nd consecutive year of decline in the share of children within the total population [1].
Among 38 countries with populations over 40 million, Japan’s share of children under 15 is the second lowest. Only South Korea recorded a lower percentage at 10.2%, while Italy and Spain had higher shares at 11.7% and 12.6%, respectively [1].
The age breakdown of Japan's child population under 15 showed 3.09 million aged 12 to 14, 2.96 million aged 9 to 11, 2.68 million aged 6 to 8, 2.43 million aged 3 to 5, and 2.13 million aged 0 to 2 [1].
These estimates are based on the 2020 census data. Updated data by prefecture from the 2025 census are expected to be released at a later date [1].