A specific conductivity measurement method includes: performing first measurement to obtain a resonance frequency f1 that is outputted to a measuring device when the first and second dielectric flat plates each have a thickness t1, and an unloaded Qu1 that corresponds to the resonance frequency f1; performing second measurement to obtain a resonance frequency f2 that is outputted to the measuring device when the first and second dielectric flat plates each have a thickness t2 that is different from the thickness t1, and an unloaded Qu2 that corresponds to the resonance frequency f2; and calculating a specific conductivity σr of the copper foil and the first and second conductor flat plates based on an arithmetic equation that includes the resonance frequency the unloaded Qu1, the resonance frequency f2, and the unloaded Qu2.