The Keisei 3400 series (京成3400形) is a three-door commuter electric multiple unit (EMU) train type operated by the private railway operator Keisei Electric Railway in the Tokyo area of Japan since 1993.

[2] The trains do not typically run on the Narita Sky Access Line.

[3] As of 1 April 2016[update], the fleet consists of five eight-car sets, formed as shown below, with six motored cars.

[4] The 3400 series trains entered service in 1993, and were built using the underframes and control equipment from the original AE series Skyliner Limited Express EMUs and steel bodies based on the (stainless steel bodied) 3700 series EMUs.

[6][5] As of September 2023,[update] one 3400 series set remains in operation.