The Toei Subway lines were originally licensed to the Teito Rapid Transit Authority (the predecessor of Tokyo Metro) but were constructed by the Tokyo Metropolitan Government following transfers of the licenses for each line.

The subway has run at a financial loss for most of its history due to high construction expenses, particularly for the Oedo Line.

Tokyo Metro and Toei trains form completely separate networks.

The Toei Subway is made up of four lines operating on 109.0 kilometers (67.7 mi) of route.

[1] Two of the lines have different colors for their station signs: Asakusa (Vermilion A) and Shinjuku (Lime S).