PROBLEM TO BE SOLVED: To provide a method for regulating the optimum actual time vulcanization through the impedance measurement and analysis of a polymeric substance, capable of accurately evaluating the internal physical characteristics of a vulcanized sample depending on time in a vulcanizing process. SOLUTION: In the method for regulating the optimum actual time vulcanization of the vulcanized sample and determining the optimum content of the component of the vulcanizing polymeric substance, the impedance of the vulcanized sample is measured during the advance of an actual vulcanizing process within a wide-band frequency range in order to evaluate the physical properties of the vulcanized sample and the measured impedance data is analyzed and fitted to acquire a plurality of parameters. The macromolecule resistance value Rp among a plurality of the acquired parameters is calculated with respect to the advance time of the vulcanizing process and a point of time when the increase speed of the calculated macromolecule resistance value Rp becomes slow suddenly is selected as the optimum vulcanizing stop time and, when the macromolecule resistance value Rp of the sample after the completion of vulcanization becomes minimum, the optimum contents of the respective components consisting the vulcanizing composition concerned are selected. COPYRIGHT: (C)2003,JPO