A self-discharge inspection method for a power storage device having a property that while the power storage device is pressed under a first load and charged with a first device voltage, in which a device voltage decreases when a load is reduced from the first load, includes detecting the first device voltage of the power storage device pressed under the first load and charged, continuously applying a power-supply voltage equal to the first device voltage from an external power supply, detecting a power-supply current flowing to the power storage device, determining a self-discharge state of the power storage device based on the detected power-supply current, and reducing the load applied to the power storage device from the first load by a load reduction amount before the power-supply current stabilizes after start of the voltage continuously applying.