A MEA is set in a state where a hydrogen gas is continuously supplied to both an anode-side electrode and a cathode-side electrode. In this state, a current is applied from an external power supply unit to the anode-side electrode and the cathode-side electrode so that the cathode-side electrode has a higher potential and that the current value gradually increases. Upon applying the current in this way, measured voltages between both electrodes measured by a voltage measurement unit are plotted in time series, thereby measuring the voltage transition across the inspection object MEA. A power generation performance inspection of the inspection object MEA is carried out based on the measured voltage transition.