Japan's population of 128 million will shrink by one-third, and seniors will account for 40 percent of people by 2060, according to a Japanese government report.
Japanese parents aren't having enough children to replace the people who are dying, according to an estimate released Monday by the Health and Welfare Ministry.
Experts say Japan will lose a million people a year for decades and by 2060, the country's population will be 87 million.
The island nation's rapidly aging population is living longer, while its work force is shrinking. That, in effect, will put increasing pressure on those who are still working to pay enough in taxes to help support the older population.
Analysts say Japan must reform its pension and social security systems and other policies to be ready for the coming changes.
"Pension programs, employment and labor policy, and social security system in this country is not designed to reflect such rapidly progressing population decline or aging," Noriko Tsuya, a demography expert at Keio University, said on public broadcaster NHK.
"The government needs to urgently revise the system and implement new measures based on the estimate," he added.