The is a DC electric multiple unit (EMU) train type operated by East Japan Railway Company (JR East) on local services in the Niigata area since 6 December 2014.
Built at the J-TREC factory in Niitsu, Niigata, the stainless steel body and "universal design" interior is derived from the E233 series commuter EMU. Externally, trains are finished in a livery with and stripes. The trains have a maximum speed of .
E129 series trains operate on the following lines, completely replacing older 115 series sets by around 2017.
The E129 series trains can operated in multiple, to form 2+2, 2+4, and 2+2+2 formations, but do not operate in multiple with E127 series trains except in emergencies.
the E129 series fleet consists of 34 two-car sets (68 vehicles) numbered A1 to A34 and 27 four-car sets (108 vehicles) numbered B1 to B27. All sets are based at Niigata Depot.
The two-car sets, A1 to A34, consist of two motored cars, each with one powered bogie, and are formed as shown below.
The four-car sets, B1 to B27, consist of four motored cars, each with one powered bogie, and are formed as shown below.
Passenger accommodation consists of a mix of transverse seating bays and longitudinal bench seating. LED lighting is used throughout. Longitudinal seats have a width of per person, wider than for the earlier E127 series trains, and the seating pitch for transverse seating bays is , approximately wider than E233 series trains. Floor height is , the same as for E127 series trains, and lower than the floor height of 115 series trains.
Initial details of the new trains were announced by JR East in July 2013. The first two two-car sets, A1 and A2, were delivered on 8 October 2014, with test-running commencing the same day.
The first trains entered revenue service on 6 December 2014.
, the fleet is as follows.
Delivery of three two-car sets from J-TREC in Niitsu began in March 2020. They are derived from the E129 series and are scheduled to replace the 115 series currently operated by Shinano Railway. These trains were put into service of rapid trains operated by Shinano Railway starting from 4 July 2020.