A power supply system comprising: a power receiving circuit; and a power transmission circuit configured to wirelessly supply power to the power receiving circuit, wherein the power transmission circuit includes a power transmission resonance circuit including an inductor having self-inductance L1 and a capacitor having capacity C1, the power receiving circuit includes a power receiving resonance circuit including an inductor having self-inductance L2 and a capacitor having capacity C2, the power transmission resonance circuit is configured to be driven at a driving frequency ω and thereby to perform power transmission from the power transmission circuit to the power receiving circuit, the self-inductance L1, the capacity C1, the self-inductance L2, the capacity C2, and the driving frequency ω are set such that an absolute value of a reactance X1 of the power transmission resonance circuit, which is determined by the self-inductance L1, the capacity C1, and the driving frequency ω, is larger than a first threshold Th1 that is not smaller than 0 and also a reactance X2 of the power receiving resonance circuit, which is determined by the self-inductance L2, the capacity C2, and the driving frequency ω, is 0, which in addition includes a case in which there is an error with which, in terms of an operation of the power receiving circuit, the condition that X2 is 0 is substantially satisfied, and the power supply system includes a detection unit configured to detect a no-load state of the power receiving circuit, based on at least one of a DC voltage, a DC current, a voltage of the inductor having self-inductance L1, a current of the inductor having self-inductance L1, or temperature of the inductor having self-inductance L1 in the power transmission circuit. a power receiving circuit; and a power transmission circuit configured to wirelessly supply power to the power receiving circuit, wherein the power transmission circuit includes a power transmission resonance circuit including an inductor having self-inductance L1 and a capacitor having capacity C1, the power receiving circuit includes a power receiving resonance circuit including an inductor having self-inductance L2 and a capacitor having capacity C2, the power transmission resonance circuit is configured to be driven at a driving frequency ω and thereby to perform power transmission from the power transmission circuit to the power receiving circuit, the self-inductance L1, the capacity C1, the self-inductance L2, the capacity C2, and the driving frequency ω are set such that an absolute value of a reactance X1 of the power transmission resonance circuit, which is determined by the self-inductance L1, the capacity C1, and the driving frequency ω, is larger than a first threshold Th1 that is not smaller than 0 and also a reactance X2 of the power receiving resonance circuit, which is determined by the self-inductance L2, the capacity C2, and the driving frequency ω, is 0, which in addition includes a case in which there is an error with which, in terms of an operation of the power receiving circuit, the condition that X2 is 0 is substantially satisfied, and the power supply system includes a detection unit configured to detect a no-load state of the power receiving circuit, based on at least one of a DC voltage, a DC current, a voltage of the inductor having self-inductance L1, a current of the inductor having self-inductance L1, or temperature of the inductor having self-inductance L1 in the power transmission circuit.