Finance History | Japan Mint, Osaka, 4 April 1871 — The Yen Acquired an Industrial Standard

On 4 April 1871, the new mint at Osaka held its opening ceremony, dated Meiji 4, second month, fifteenth day in the Japanese calendar then in use. The riverside works at Tenma supplied the industrial machinery needed for a national currency reform that would soon define the yen as Japan’s common monetary unit. Before the reform, Tokugawa-era commerce used gold, silver, and copper currencies with changing relationships, alongside domain notes and foreign coins. Exchange required local knowledge and repeated calculation, while different units complicated taxes, public accounts, long-distance prices, and contracts. The Osaka Mint changed the production side of that system. Imported machinery and foreign technical specialists supported the refining, rolling, blanking, assaying, and striking of coins to consistent specifications. A centralized mint could make a denomination reproducible across many transactions, replacing the need to judge each piece chiefly by origin or appearance. Later in 1871, the New Currency Act established the yen, sen, and rin on a decimal basis: one yen equalled one hundred sen, and one sen equalled ten rin. The law initially framed the yen through a gold standard, although silver remained essential in Asian trade and Japan’s practical monetary arrangements continued to evolve. The mechanism joined measurement to administration. Standard coins made prices easier to compare, allowed government receipts and expenditures to be stated in a common unit, and supported accounting across a more integrated national market. Assay rules and mechanized dies also made official specifications visible, turning the coin into evidence of the state’s capacity to measure and certify value. The ceremony did not instantly erase older money, and statutory reform did not guarantee an immediate supply of every denomination. Conversion, circulation, and public familiarity took time, which is why the mint’s importance lies in sustained production rather than a ceremonial switch. The cover photograph shows the present Japan Mint campus and museum area at Tenma, including later buildings within the continuing institution rather than the original 1871 main factory. The location remains the clearest public anchor for the industrial beginning of the yen. Image: “Mint Museum Osaka,” Mr.ちゅらさん, 12 April 2023, via Wikimedia Commons; CC BY-SA 4.0.