People aged 65 or older accounted for 21 percent of Japan's population in 2005, surpassing Italy's 20 percent as the world's highest, the Ministry of Internal Affairs and Communications said in a preliminary report.
The ratio of people under 15 also hit the world's lowest level at 13.6 percent, dipping below Bulgaria's 13.8 percent, according to the report based on a nationwide census taken last year.
A plunging birth rate and an expanding elderly population pose serious concerns for Japan as it struggles to tackle a labor shortage and eroding tax base.
Japan's population dropped in 2005 for the first time on record, shocking officials and spurring a spate of measures to encourage women to have more babies.
The government began a five-year project last year to build more daycare centers, while encouraging men to take paternity leave. Towns and villages have also launched matchmaking services to get more people to marry.
But the country's birthrate in 2005 stood at a record low of 1.25 babies per woman in her lifetime, far below the 2.1 rate needed to keep the population steady, according to the AP.
Japan's reluctance to open its borders to immigrants and refugees despite an urgent need for new workers to replace its aging work force has also compounded the problem.
In a weary world of endless US military interventions, sanctions, trade tariffs and chaos, let’s pause and take stock of the shining house on the hill