Provided is a power supply unit for supplying power to an electric apparatus, comprising an indicator unit, an introduction-detecting unit for detecting introduction of the electric apparatus into a vehicle for transportation of the electric apparatus, a voltage-detecting unit for detecting the voltage of the power source, a memory unit for storing a first voltage and a second voltage lower than the first voltage, a judgment unit for determining whether the voltage of the power source detected by the voltage-detecting unit is higher than the first voltage and a forced discharge unit. The forced discharge unit is configured to cause the indicator unit to notify if the electric apparatus is in a state prohibiting introduction into the vehicle and forcibly discharge the power source.