PURPOSE: To provide a method for producing wire-like material body excellent in controllability and a method and device for measuring coating resistance.

CONSTITUTION: In the method for producing the wire-like material body by making the wire-like material boy by applying a tension to a preform to wire- draw and forming a resin layer on the surface of the wire-like material body before winding, a tension (T0) exerting on the wire-like material body before coating and expressed by T0=T1-F is determined from (F), which is a measured value obtained by measuring coating resistance at the time of coating with resin, and (T1), which is a measured value obtained by measuring the tension in the longitudinal direction exerted on the wire-like material body in contact- type after forming the resin layer, and the preform is wire-drawn while continuously monitoring the (T0). It is enabled to inline-monitor the tension of the wire-like material body in a non-contact state, which is important in the tension control of such as an optical fiber before coating with resin, and the optical fiber secured in transmission characteristics in the longitudinal direction is produced.