VEHICLE-MOUNTED EMERGENCY POWER SUPPLY DEVICE

An in-vehicle emergency power supply device includes a power storage unit including an electric double-layer capacitor, a charging circuit charging the power storage unit, a discharging circuit discharging the power storage unit, and a controller controlling the charging circuit and the discharging circuit. When the charging circuit charges the power storage unit, the controller determines a set full charging voltage of the power storage unit, determines a correction charging voltage lower than the set full charging voltage based on the set full charging voltage, and controls the charging circuit to charge the power storage unit until a stored voltage reaches the correction charging voltage. This in-vehicle emergency power supply device stabilizes an output voltage thereof.