Process for producing magnetic tape

A process for producing a magnetic tape, in which a web having a greater thickness in a central portion is extended in the width direction by a extension roller apparatus comprising a backup roller for rolling the web and horizontally disposed tension rollers which elastically push the web at portions near both sides of the backup roller to allow the web for extending in the width direction before it is cut by a slitter, when the web is supplied to the slitter to be cut into several magnetic tapes,

• wherein the elastic extension of the web makes a tension of the web substantially uniform in the width direction when the web is supplied to the slitter, and
• wherein the process is carried out in a production line in which said web wound on a rewinding reel in a bulk state is rolled on a plurality of guide rollers, a ground suction drum, a plurality of guide rollers, the backup roller of the extension roller apparatus, and a plurality of guide rollers, in this order, and then supplied to the slitter, at which the web is introduced between several pairs of rotating blades and is cut into the plurality of magnetic tapes.