To observe the behavior of ceramics during sintering, such methods as measuring the degree of shrinkage in the direction of pressure application during hot pressing and observing the gases emitted from the ceramics are known. On the other hand, as electrical measurement methods, for example, in the measurement of ionic conductivity, it was possible to measure intergranular and intragranular resistance by AC impedance measurement method using AC current. However, such a method can only be applied to materials with some large ionic conductivity. In this presentation, we devised a method to determine the internal state of sintering by measuring the electrical resistance of sintered materials using nanosecond-width pulse voltage instead of AC voltage. It was found that this method has an excellent feature of being able to measure the internal resistance of a material regardless of its conductivity. The change in electrical resistivity before and after sintering is expected to be applicable to in-situ monitoring of the internal structure during sintering.