The report, released by the Japan Muslim Association, said in 1991 there were around 100,000 Muslims in the East Asian country.
It said most of them were migrant workers from different Muslim countries, IQNA’s East Asia branch reported.
According to the report, the number of Muslims in Japan is now close to 65,000 because many of the migrant workers have returned to their home country.
Expat Muslims living in Japan are mostly from Indonesia, Bangladesh, and Pakistan.
The Japan Muslim Association puts the number of native Japanese Muslims in the country at around 10,000.
Shinto and Buddhism are the predominant religions of Japan.