The Tobu 9000 series is a DC electric multiple unit (EMU) commuter train type operated by the private railway operator Tobu Railway in Japan since 1981.

The Tobu Railway Company, Ltd. is a Japanese commuter railway and keiretsu holding company in the Greater Tokyo Area as well as an intercity and regional operator in the Kantō region. Excluding the Japan Railways Group companies, Tobu's 463.3 km (287.9 mi) rail system is the second longest in Japan after Kintetsu. It serves large portions of Saitama Prefecture, Gunma Prefecture and Tochigi Prefecture, as well as northern Tokyo and western Chiba Prefecture. The Tobu Railway Company is listed in the First Section of the Tokyo Stock Exchange and is a constituent of the Nikkei 225 index.