A method of manufacturing a metallic fiber in which from a convergent extended wire, which is formed by a metallic fiber and a matrix member which is formed of a metallic material and whose dissolvability is higher than the dissolvability of the metallic fiber, the matrix member is continuously dissolved and removed by an electrolytic processing in a plurality of electrolytic tanks which are arranged in the conveying direction of the convergent extended wire, wherein: the convergent extended wire is passed through electrolytes in the plurality of electrolytic tanks, which are arranged in the shape of a gentle convex arch at the vertical direction upper side which includes the conveying passage of the convergent extended wire, the convergent extended wire is passed above a plurality of feeding devices which are provided at the outer sides of the electrolytes and which are disposed in the same arch-shape so as to correspond to the electrolytic tanks, in each of the plurality of electrolytic tanks, the metallic fiber is maintained in one of a cathode reduction area and a passivation area, or alternatively, anode current is maintained at a predetermined potential which is closer to 0, and the matrix member is anode-electrolyzed. At this time, a method of manufacturing the twine of metallic fibers, further including the step of: intertwining the convergent extended member in the unit of two to four before the electrolytic processing, while the convergent extended member is formed by a forming device in a spiral shape whose diameter is larger than the diameter of a closely-intertwined twine.