Data released on Thursday by the Japanese government shows the number of babies born in 2020 fell to 840,832, down 2.8 per cent or 24,407 compared to 2019.
It is the first time the country has recorded fewer than 900,000 births since records began.
The number of registered marriages in Japan has also fallen by 12.3 per cent, to 525,490, a post-war record, the health ministry said. The country has a total population of around 126 million.
The records also suggest the birth rate could decline even further, with the number of newborns falling 9.2 per cent in the January to March period.
The data suggests people are putting off getting married and starting a family amid financial instability as a result of the pandemic.
Japan has one of the lowest fertility rates in the world and the number of births has consistently fallen since 1973.
Politicians have raised concerns over the effect of the declining birth rate on the country’s economy in areas including the job and housing markets.
Experts say Japan’s shrinking population can be attributed to young people focusing on their careers and abstaining from sex and marriage, while senior citizens are living longer than ever.
The age of people giving birth to a child is also increasing, with the average age at the time of a first child being 30.7 years.
Shinzo Abe, Japan’s prime minister from 2012-2020, previously described the low birth rate as a “national crisis” and promised a series of reforms aimed at helping alleviate burdens on families which discourage them from having children.