The internal affairs ministry estimates that, as of last Thursday, there were a record 36.27 million people aged 65 or older in Japan, up 60,000 from last year.
The ministry says 15.74 million of them were men, and 20.53 million were women.
They make up 29.1 percent of Japan's population, an increase of 0.3 percentage points from last year.
Data compiled by the United Nations show that this figure is the highest among countries and territories with a population of more than 100,000.
The figure is 5 percentage points higher than the one for Italy, which is a distant second.
The ministry says the number of elderly workers in Japan reached a record 9.09 million last year.
The ratio of workers aged 65 or older to the elderly population is 25.1 percent, one of the highest among the major countries.
The ministry says 50.3 percent of people between 65 and 69 have jobs. The ratio rose by 0.7 percentage points from the previous year to top 50 percent for the first time.
Since April last year, companies have been required to try to keep their workers on the payroll until age 70, if they wish.
The ministry says the number of elderly workers is expected to continue to grow.