The Bank of Japan was established under the Bank of Japan Act (promulgated in June 1882) and began operating on October 10, 1882, as the nation's central bank. The Bank was reorganized on May 1, 1942 in conformity with the Bank of Japan Act (hereafter the Act of 1942), promulgated in February 1942. The Act of 1942 strongly reflected the wartime situation: for example, Article 1 stated the objectives of the Bank as "the regulation of the currency, control and facilitation of credit and finance, and the maintenance and fostering of the credit system, pursuant to national policy, in order that the general economic activities of the nation might adequately be enhanced." The Act of 1942 was amended several times after World War II. Such amendments included the establishment of the Policy Board as the Bank's highest decision-making body in June 1949.
The Act of 1942 was revised completely in June 1997 under the two principles of "independence" and "transparency." The revised act (the Act) came into effect on April 1, 1998.