A power transfer system comprising: a power transmitting device having a transmitting-device-side first electrode, a transmitting-device-side second electrode, and a feeding circuit (13S,XG,LG) configured to feed an alternating voltage between the transmitting-device-side first electrode and the transmitting-device-side second electrode; and a power receiving device having a receiving-device-side first electrode, a receiving-device-side second electrode, and a load circuit configured to receive an alternating voltage generated between the receiving-device-side first electrode and the receiving-device-side second electrode, wherein a receiving-device-side reference potential point is connected to a reference potential of the receiving device, the receiving-device-side reference potential point being a node between the load circuit and the receiving-device-side second electrode or being a midpoint of the load circuit; the power transmitting device includes a series circuit between the transmitting-device-side first electrode and the transmitting-device-side second electrode such that a first element is connected to the transmitting-device-side first electrode, the series circuit being formed by the first element and a second element connected in series; a transmitting-device-side reference potential point is connected to a reference potential of the transmitting device, the transmitting-device-side reference potential point being a node between the first element and the second element of the series circuit; and the series circuit is provided such that a balance condition Z1 × Z4 = Z2 × Z3 is satisfied or can be nearly satisfied at a fundamental frequency of the alternating voltage, where Z1 represents an impedance of the first element, Z2 represents an impedance of the second element, Z3 represents an impedance of a series circuit including a capacitance (Ca) formed between the transmitting-device-side first electrode and the receiving-device-side first electrode and the load circuit, and Z4 represents an impedance including a capacitance formed between the transmitting-device-side second electrode and the receiving-device-side second electrode. a power transmitting device having a transmitting-device-side first electrode, a transmitting-device-side second electrode, and a feeding circuit (13S,XG,LG) configured to feed an alternating voltage between the transmitting-device-side first electrode and the transmitting-device-side second electrode; and a power receiving device having a receiving-device-side first electrode, a receiving-device-side second electrode, and a load circuit configured to receive an alternating voltage generated between the receiving-device-side first electrode and the receiving-device-side second electrode, wherein a receiving-device-side reference potential point is connected to a reference potential of the receiving device, the receiving-device-side reference potential point being a node between the load circuit and the receiving-device-side second electrode or being a midpoint of the load circuit; the power transmitting device includes a series circuit between the transmitting-device-side first electrode and the transmitting-device-side second electrode such that a first element is connected to the transmitting-device-side first electrode, the series circuit being formed by the first element and a second element connected in series; a transmitting-device-side reference potential point is connected to a reference potential of the transmitting device, the transmitting-device-side reference potential point being a node between the first element and the second element of the series circuit; and the series circuit is provided such that a balance condition Z1 × Z4 = Z2 × Z3 is satisfied or can be nearly satisfied at a fundamental frequency of the alternating voltage, where Z1 represents an impedance of the first element, Z2 represents an impedance of the second element, Z3 represents an impedance of a series circuit including a capacitance (Ca) formed between the transmitting-device-side first electrode and the receiving-device-side first electrode and the load circuit, and Z4 represents an impedance including a capacitance formed between the transmitting-device-side second electrode and the receiving-device-side second electrode.