To provide a card PC that is used by being installed on a motherboard of an electronic device and in which neither breakdown nor malfunction occurs in the semiconductors regardless of the supply voltage of the motherboard.

The card PC 10 is used by being installed on the electronic device through an interface connector 30 that has plural pins. It is equipped with two circuit sections and protection circuits. The circuits in the first section and protection circuits 13 and 14 operate by the first power source voltage supplied from the electronic device through pins of the interface connector 30. The protection circuits output the second power source voltage when the second voltage value is within the specified limits, and do not output the second power source voltage when the second voltage value is outside the specified limits. The circuits in the second section operate by the second power source voltage supplied from the protection circuits.