Ehime愛媛県
Seiyo 西予市
Data last updated:
Seiyo, Ehime, Japan has a population of 31,628 (2025 national census). IPSS projections estimate 28,848 by 2030 and 18,200 by 2050 (a decrease of about 48.6% from 2020), with the share of residents aged 65+ rising from 44.1% in 2020 to 54.0%.Sources: Japan Census (Statistics Bureau), IPSS Regional Population Projections (2023)
2025
(Census)
31,628
2030
(Projection)
28,848
▼ -18.5%
2040
(Projection)
23,128
▼ -34.6%
2050
(Projection)
18,200
▼ -48.6%
Change vs. 2020 census
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Other municipalities in Ehime (愛媛県)
Data Sources
- Portal Site of Official Statistics of Japan (e-Stat)（https://www.e-stat.go.jp/）
- National Institute of Population and Social Security Research (IPSS), Regional Population Projections (2023 ed.)
* This service uses the e-Stat API but its content is not guaranteed by the Japanese government.
Seiyo Population Table (1980–2050)
Population by year: national census results (restated to current municipal boundaries) and IPSS (2023) projections based on the 2020 census.
| Year | Population | vs 2020 | Type |
|---|---|---|---|
| 1980 | 56,175 | ▲ +58.7% | Census |
| 1985 | 54,804 | ▲ +54.9% | Census |
| 1990 | 51,893 | ▲ +46.6% | Census |
| 1995 | 49,022 | ▲ +38.5% | Census |
| 2000 | 47,217 | ▲ +33.4% | Census |
| 2005 | 44,948 | ▲ +27.0% | Census |
| 2010 | 42,080 | ▲ +18.9% | Census |
| 2015 | 38,919 | ▲ +10.0% | Census |
| 2020 | 35,388 | — | Census |
| 2025 | 31,628 | ▼ -10.6% | Census |
| 2030 | 28,848 | ▼ -18.5% | Projection |
| 2035 | 25,881 | ▼ -26.9% | Projection |
| 2040 | 23,128 | ▼ -34.6% | Projection |
| 2045 | 20,560 | ▼ -41.9% | Projection |
| 2050 | 18,200 | ▼ -48.6% | Projection |
About Seiyo
Overview
Seiyo (西予市) is a municipality in Ehime, Japan, with a population of 31,628 as of 2025.
Population Projection of Seiyo
According to projections by Japan's National Institute of Population and Social Security Research (IPSS), Seiyo's population is expected to reach 28,848 by 2030 (-18.5%), 23,128 by 2040 (-34.6%), and 18,200 by 2050 (-48.6%). A significant population decline is projected over the next three decades.
Aging Rate of Seiyo
The aging rate (percentage of residents aged 65 and over) is 44.1% as of 2020 and is projected to rise to 54.0% by 2050. More than half of residents will be seniors, placing the town in the "marginal municipality" category.
National Comparison
Seiyo is experiencing one of the faster rates of population decline in Japan.
National and Prefectural Rank
- Population decline rate: Ranked #392 out of 1903 municipalities nationwide.
- Aging rate in 2050: Ranked #328 out of 1903 nationwide.
- Population size: Ranked #872 out of 1917 nationwide.
- Related: National rankings / All municipalities in Ehime
Earnings in Ehime (愛媛県): Average salary in Ehime (愛媛県) by age, gender and company sizejpsalary / MHLW Basic Survey on Wage Structure