The Bank of Tokyo-Mitsubishi UFJ, Ltd. (BTMU; 株式会社三菱東京UFJ銀行, Kabushiki kaisha mitsubishi tōkyō yūefujei ginkō^?) is the largest bank in Japan, which was established on January 1, 2006, with the merger of the Bank of Tokyo-Mitsubishi, Ltd. and UFJ Bank Ltd. The bank serves as the core retail and commercial banking arm of the Mitsubishi UFJ Financial Group.

As at 31 October 2010 BTMU was ranked by Bloomberg as the largest bank in Japan and the eighth largest in the world.

The bank's head office is in Marunouchi, Chiyoda, Tokyo, Japan, with 772 other offices in Japan and 76 offices overseas.

BTMU dates back to 1880 as the Mitsubishi Bank, Ltd. (株式会社三菱銀行, Kabushiki kaisha mitsubishi ginkō^?) was founded by former samurai Iwasaki Yatarō, and was a core member of Mitsubishi Group companies. Also, in 1880, the Yokohama Specie Bank was established, which was the forerunner of the Bank of Tokyo, Ltd. (株式会社東京銀行, Kabushiki kaisha tōkyō ginkō^?), established in 1945 with most of Yokohama Specie Bank's assets. In April 1996, the Mitsubishi Bank, Ltd. and the Bank of Tokyo, Ltd. merged into the Bank of Tokyo-Mitsubishi, Ltd. (株式会社東京三菱銀行, Kabushiki kaisha tōkyō mitsubishi ginkō^?), becoming the world's largest bank in terms of total assets.