Japan's elderly people accounted for 28 percent of its population in 2018, the highest proportion in the world.
Japanese government data showed on Sunday the number of those aged 65 or older stood at around 35.9 million people, up point-3 percent from the year before.
Italy was second in the chart with 23 percent, followed by Portugal, Finland and Greece.
South Korea's elderly account for 15 percent of its population.
Japan's National Institute of Population and Social Security Research said, however, that South Korea will top the chart by 2050 mainly due to its extremely low birth rate.