A non-contact power supply device includes: a power transmission coil that generates a magnetic flux by an alternating current; a power transmission circuit that supplies the alternating current to the power transmission coil; a power transmission side control circuit that controls the power transmission circuit; a power receiving coil that generates an alternating current by interlinking the magnetic flux generated in the power transmission coil; and a power receiving circuit that converts the alternating current supplied from the power receiving coil into a direct current, and supplies the direct current to the power supply target. The power transmission side control circuit obtains a voltage vector target value based on a relationship between a voltage vector and a current vector, and controls the power transmission circuit to set the voltage vector of the alternating current output from the power transmission circuit to be the voltage vector target value.