A circuit, comprising: a vehicle-side connector, provided in an electrically driven vehicle, and configured to be connected to a charger-side connector which is provided in an external charger for supplying power to a battery installed in the electrically driven vehicle; and a vehicle-side circuit, provided at the electrically driven vehicle, and configured to be connected via a connecting part to the charger-side connector being grounded in a state that the vehicle-side connector and the charger-side connector are connected to each other, the vehicle-side circuit includes: a power source; a first resistor provided between the power source and the connecting part; a second resistor which is connected to the first resistor in series; a switch which turns on or off current supply from the power source; a voltage detector which detects a voltage at a connection point of the first resistor and the second resistor; and a determining part which determines a state of connection between the vehicle-side connector and the charger-side connector and occurrence of a failure in the vehicle-side circuit based at least in part on the voltage detected by the voltage detector and an on/off state of the switch, characterized in that said second resistor is provided between the first resistor and the connecting part, and is connected directly in series with the first resistor. a vehicle-side connector, provided in an electrically driven vehicle, and configured to be connected to a charger-side connector which is provided in an external charger for supplying power to a battery installed in the electrically driven vehicle; and a vehicle-side circuit, provided at the electrically driven vehicle, and configured to be connected via a connecting part to the charger-side connector being grounded in a state that the vehicle-side connector and the charger-side connector are connected to each other, the vehicle-side circuit includes: a power source; a first resistor provided between the power source and the connecting part; a second resistor which is connected to the first resistor in series; a switch which turns on or off current supply from the power source; a voltage detector which detects a voltage at a connection point of the first resistor and the second resistor; and a determining part which determines a state of connection between the vehicle-side connector and the charger-side connector and occurrence of a failure in the vehicle-side circuit based at least in part on the voltage detected by the voltage detector and an on/off state of the switch, characterized in that said second resistor is provided between the first resistor and the connecting part, and is connected directly in series with the first resistor. a power source; a first resistor provided between the power source and the connecting part; a second resistor which is connected to the first resistor in series; a switch which turns on or off current supply from the power source; a voltage detector which detects a voltage at a connection point of the first resistor and the second resistor; and a determining part which determines a state of connection between the vehicle-side connector and the charger-side connector and occurrence of a failure in the vehicle-side circuit based at least in part on the voltage detected by the voltage detector and an on/off state of the switch, characterized in that said second resistor is provided between the first resistor and the connecting part, and is connected directly in series with the first resistor.