An electric apparatus with a power supply including a electric double layer capacitor capable of being charged in a short time and supplying a constant electric power with a high power efficiency, and in a peak load type electric apparatus such as an electric automobile, a long time small power output and a short time large power output can be derived as required. For a constant load type electric apparatus, electric power is supplied from an electric double layer capacitor of a power supply, and is stabilized to a constant voltage by a switching regulator, and for a peak load type electric apparatus, a power supply is made by connecting a first electric double layer capacitor of a high energy density type to a second electric double layer capacitor of a high power density type via a current output type switching regulator, and the second capacitor is charged with electric power in the first capacitor through the switching regulator. The output power is always derived from the second capacitor of high power density.