The present invention relates to an apparatus for measuring interfacial impedance between the body and a stimulating electrode, comprising: a first electrode connected to some cells in the body； a second electrode connected to other cells in the body so as to provide a current which is applied by a stimulator to the first electrode through the cells； a measurement unit for selectively extracting voltages loaded on the first and second electrodes according to currents applied to the first and second electrodes； a charge storage unit to which a relative potential corresponding to a voltage difference between the first and second electrodes is stored； an A/D conversion unit for converting the signal corresponding to the relative potential into a digital signal and for outputting the digital signal； and an impedance calculation unit for calculating the interfacial impedance between the first and second electrodes according to the digital signal outputted from the A/D conversion unit and the current applied to the second electrode. Therefore, according to the present invention, interfacial impedance between the body and a stimulating electrode implanted to the brain or muscle of the body can be measured by using the difference in voltages loaded on each electrode.
