This is a list of Railway Electrification Systems in Japan: Overhead line power supply, unless otherwise noted. The rail system consists of the following ():
of , of which is electrified; of , all electrified; of Scotch gauge, all electrified; of narrow gauge, all electrified.
Electrification systems used by the Japan Railways Group, Japan's formerly state-owned operators, are 1,500 V DC and 20 kV AC for conventional lines and mini Shinkansen and 25 kV AC for Shinkansen. Electrification at 600 V DC and 750 V DC are also seen in private lines and non-rail based transit systems. The frequency of the AC power supply is 50 Hz in Eastern Japan and 60 Hz in Western Japan.