203系は、常磐線用に201系から派生した形式です。銀色のアルミ車体、前面貫通扉、チョッパ制御装置を備えています。車内は201系と同じです。常磐線の取手と東京メトロ千代田線の代々木上原の間を走ります。E233系2000番台への置き換えが進んでおり、数年以内に引退すると見込まれています。
Series 203 is a derivative of Series 201 for the Joban Line. It has an aluminum silver body, a front gangway door, and a chopper control system. The interior is the same as that of Series 201. The trains run between Toride on the Joban Line and Yoyogi-uehara on the Tokyo Metro Chiyoda Line. They are being replaced by Series E233-2000 and are expected to be withdrawn within a few years.