A non-contact power supply device for supplying electric power to a non-contact power reception device comprising a power reception coil and a load circuit to which the electric power received by the power reception coil is supplied when connected to the power reception coil, the non-contact power supply device comprising: a power transmission coil configured to be electromagnetically coupled with the power reception coil; a power transmission circuit configured to transmit electric power by the power transmission coil; and a control circuit configured to drive the power transmission circuit by using electric power of either a first voltage or a second voltage lower than the first voltage, wherein the control circuit is configured to: drive the power transmission circuit by using the electric power of the second voltage to carry out an authentication processing with the non-contact power reception device; and when the authentication processing is successful, drive the power transmission circuit by using the electric power of the second voltage to carry out a first foreign object detection processing for detecting a foreign object, (ACT 15) characterized in that if the foreign object is not detected in the first foreign object detection processing, the control circuit is configured to change the voltage from the second voltage to the first voltage (ACT 16), and carry out a second foreign object detection processing (ACT 17), in the second foreign object detection processing, if the determination of the absence of the foreign object is confirmed, (ACT 35) the control circuit is configured to transmit a signal instructing connection of the load circuit to the non-contact power reception device (ACT 36), and the control circuit is configured to detect completion of a charging processing in the non-contact power reception device, (ACT 19) and lower the voltage from the first voltage to the second voltage (ACT 20). a power transmission coil configured to be electromagnetically coupled with the power reception coil; a power transmission circuit configured to transmit electric power by the power transmission coil; and a control circuit configured to drive the power transmission circuit by using electric power of either a first voltage or a second voltage lower than the first voltage, wherein the control circuit is configured to: drive the power transmission circuit by using the electric power of the second voltage to carry out an authentication processing with the non-contact power reception device; and when the authentication processing is successful, drive the power transmission circuit by using the electric power of the second voltage to carry out a first foreign object detection processing for detecting a foreign object, (ACT 15) characterized in that if the foreign object is not detected in the first foreign object detection processing, the control circuit is configured to change the voltage from the second voltage to the first voltage (ACT 16), and carry out a second foreign object detection processing (ACT 17), in the second foreign object detection processing, if the determination of the absence of the foreign object is confirmed, (ACT 35) the control circuit is configured to transmit a signal instructing connection of the load circuit to the non-contact power reception device (ACT 36), and the control circuit is configured to detect completion of a charging processing in the non-contact power reception device, (ACT 19) and lower the voltage from the first voltage to the second voltage (ACT 20). drive the power transmission circuit by using the electric power of the second voltage to carry out an authentication processing with the non-contact power reception device; and when the authentication processing is successful, drive the power transmission circuit by using the electric power of the second voltage to carry out a first foreign object detection processing for detecting a foreign object, (ACT 15) characterized in that if the foreign object is not detected in the first foreign object detection processing, the control circuit is configured to change the voltage from the second voltage to the first voltage (ACT 16), and carry out a second foreign object detection processing (ACT 17), in the second foreign object detection processing, if the determination of the absence of the foreign object is confirmed, (ACT 35) the control circuit is configured to transmit a signal instructing connection of the load circuit to the non-contact power reception device (ACT 36), and the control circuit is configured to detect completion of a charging processing in the non-contact power reception device, (ACT 19) and lower the voltage from the first voltage to the second voltage (ACT 20).