To provide an electric wire drum supporting device which can measure the wine length simply while the function required of a wire feeder device is well secured, and which can reduce the influence of eventual error at the time of measuring the wire length depending upon the amount of wire being wound.

A supporting rod 12 installed overhead of a pair of supporting side plates 11 and supporting an electric wide drum A rotatably and a coupling member 13 installed in the area under the side plates 11 are formed from a ferromagnetic substance, and a magnetic path forming part 14 having magnetism conductivity is installed on the side plate 11, and an energizing coil 3 is mounted in the magnetic path formed thereby in such a way as interposed in between, and the induced voltage in the electric wire W when an energizing current is sent to the coil 3 is measured, the result wherefrom is used to calculate the number of turns of the wire W wound.