NOVELTY - An internal state monitoring device (100) comprises collecting portion (111) for collecting currents flowing through electrodes (120); sensors; load device connected to fuel cell (201) via the collecting portion and a second separator; and extracting-monitoring device for extracting alternating current components, contained in each of the measured electrode currents, generated in response to a change in the load and monitoring the distribution of a state quantity of resistance polarization in the fuel cell based on each of the extracted alternating current components.    USE - For monitoring an internal state of a fuel cell.    ADVANTAGE - The device prevents an increase in contact resistance between cell electrodes and reactant gas flow paths due to unevenness of pressure from the cell electrodes onto the flow paths. The density of measuring points can be increased with the size of sensors to maintain the sensing accuracy. Distance between contact points can be decreased and inter-contact-point resistance can be increased.    DETAILED DESCRIPTION - The internal state monitoring device for fuel cell having electrolyte and separators (203, 204) sandwiching the electrolyte, comprises electrodes for electrical conduction with regions on a surface of first separator through contact at prescribed contact points in fuel cell; collecting portion for collecting currents flowing through the electrodes to give the same electric potential to the electrodes; sensors for measuring electrode currents flowing through the electrodes; load device connected to the fuel cell via the collecting portion and a second separator for variably controlling a load applied between the collecting portion and the second separator; and extracting-monitoring device for extracting alternating current components, contained in each of the measured electrode currents, generated in response to a change in the load and monitoring the distribution of a state quantity of resistance polarization in the fuel cell based on each of the extracted alternating current components. An INDEPENDENT CLAIM is included for a state monitoring method for fuel cell.    DESCRIPTION OF DRAWING(S) - The figure is a view of the internal state monitoring device and the fuel cell.    Monitoring device (100)    Collecting portion (111)    Electrodes (120)    Fuel cell (201)    Separators (203, 204)