内部線は、日本で大変珍しくなった、762mm ナローゲージの路線です。四日市市内線の性格を持ち、ある程度の乗降客を持ちます。2009年現在は近鉄の運営です。車両は、近代化によって投入された 260,160形のほか、三重交通時代からの引継車である130形も走っています。電動車は全て吊掛式です。
Ustube line is a narrow gauge(762mm) line in Yokkaichi city. Operated by Kintetsu train company. The Utsube Line has a 762 mm narrow gauge, now very rare in Japan. It functions as an urban railway within Yokkaichi and carries a reasonable number of passengers. As of 2009, it is operated by Kintetsu. Its rolling stock includes Types 260 and 160 introduced during modernization, as well as Type 130 inherited from the Mie Kotsu era. All motor cars use nose-suspended drives.