The 207 series (207系) or 207–900 series (207系900番台) was a commuter electric multiple unit (EMU) train type introduced in 1986 by Japanese National Railways (JNR) and operated by East Japan Railway Company on through services between the Joban Line and Tokyo Metro Chiyoda Line. Only one 10-car set was built, which was withdrawn in December 2009.

The Tokyo Metro Chiyoda Line is a subway line owned and operated by Tokyo Metro in Tokyo, Japan. On average, the line carries 1,447,730 passengers daily (2017), the second highest of the Tokyo Metro network, behind the Tozai Line (1,642,378).