Sony Music Entertainment (Japan) Inc. (株式会社ソニー・ミュージックエンタテインメント, Kabushiki gaisha Sonī Myūjikku Entateinmento), often abbreviated as SMEJ or simply SME, and also known as Sony Music Japan for short (stylized as SonyMusic), is a Japanese music arm for Sony. Founded in 1968 as CBS/Sony, SMEJ is directly owned by Sony Group Corporation and is operating independently from the United States–based Sony Music Entertainment due to its strength in the Japanese music industry. Its subsidiaries include the Japanese animation production enterprise, Aniplex, which was established in September 1995 as a joint-venture between Sony Music Entertainment Japan and Sony Pictures Entertainment Japan, but which in 2001 became a wholly owned subsidiary of Sony Music Entertainment Japan. It was prominent in the early to mid 1990s producing and licensing music for animated series such as Roujin Z from acclaimed Japanese comic artist Katsuhiro Otomo and Capcom's Street Fighter animated series.

Until March 2007, Sony Music Japan also had its own North American sublabel, Tofu Records. Releases of Sony Music Japan now appear on Columbia Records and/or Epic Records in North America.

Sony does not have the trademark rights to the Columbia name in Japan, so releases under Columbia Records from another country appears on Sony Records in Japan, but retains the usage of the "walking eye" logo. The Columbia name and trademark is controlled by Nippon Columbia, which was, in fact, the licensee for the American Columbia Records up until 1968, even though relations were officially severed as far back as World War II. Nippon Columbia also does not have direct relations with the British Columbia Graphophone Company (an EMI subsidiary), so the licensee for the British Columbia Graphophone Company was actually Toshiba Musical Industries.

With Sony Corporation of America's buyout of Bertelsmann's stake in Sony BMG, Sony Music Entertainment Japan stepped in to acquire outstanding shares of BMG Japan from Sony BMG, making it a wholly owned subsidiary of Sony Music Japan.

The idea for a CBS/Sony joint venture came in 1967 from Harvey Schein, then President of Columbia Records International, who had spent a decade traveling the world building CBS's international company. In 1972 Schein would leave CBS to become the president of Sony Corporation of America.

Sony Music Entertainment Japan was officially incorporated in March 1968 as a Tokyo-based 50/50 joint venture between Sony and U.S. conglomerate CBS to distribute the latter's music releases in Japan. The company was incorporated as CBS/Sony Records and with Sony co-founder Akio Morita as president.

Norio Ohga, who himself was a musician, was part of the management team from the formation of the company and served as president and representative director since April 1970. In 1972, when CBS/Sony was generating robust profits, Ohga was named chairman and at the same time gained further responsibility and influence within Sony. He would continue to work for the music company one morning a week. In 1980, Toshio Ozawa succeeded Ohga as president.

In 1983, the company was renamed CBS/Sony Group.