Currency Museum Bank of Japan
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FAQ currency

Q5. When did the yen currency unit begin to be used?

A5. The Meiji government enacted the New Currency Act in 1871, stipulating that the yen should be used officially as the basic currency unit. The government also introduced smaller units, the sen (1/100th of the yen) and the rin (1/10th of the sen). New coins were issued by setting 1.5 grams of gold at 1 yen, and manufactured using modern Western technology. Various explanations have been given for the government's choice of the yen. First, the standardized shape of the coins was a circle, and yen means "circle" in Japanese. Second, it is said that some Japanese people familiar with the Western silver coins that had been called Yo-yen (Western yen) or Gin-yen (silver yen) in China picked up these names in Japan at the end of the Edo Period, and started to call ryo gold coins yen. Third, the new yen coins were minted by machines transferred from the British mint in Hong Kong, and it has been claimed that the yen was named after the one-yuan Hong Kong coin, since yen and yuan are written with the same Chinese character, 圓.