The E217 series (E217系) was a suburban electric multiple unit (EMU) train type operated by East Japan Railway Company (JR East) in the Kantō region of Japan from 1994 to 2025.

Introduced in 1994 to replace the 113 series EMUs running on the Sōbu Line (Rapid) and Yokosuka Line, the E217 series was the first outer-suburban train type in Japan to feature four pairs of doors per side per car. The basic design was developed from the 209 series commuter EMUs. It replaced all the Yokosuka Line 113 series trains by 1999. The trains were built jointly by Kawasaki Heavy Industries, Tokyu Car, and JR East (Niitsu and Ofuna factories).

For traction, they used Mitsubishi Electric-manufactured VVVF inverters with IGBT (formerly GTO) switching devices which control Mitsubishi MT68/73 traction motors. The gear ratio was 97:16.

The 11-car sets were based at Kamakura Depot and formed with four motored ("M") cars and seven non-powered trailer ("T") cars.

The four-car sets were based at Kamakura Depot and formed with two motored ("M") cars and two non-powered trailer ("T") cars.

Three 10-car sets (F-01–F-03) were based at Kōzu Depot and formed with four motored ("M") cars and six non-powered trailer ("T") cars.

Three five-car sets (F-51–F-53) were based at Kōzu Depot and formed with two motored ("M") cars and three non-powered trailer ("T") cars.

The E217 series trains entered revenue service from 3 December 1994.