A power supply system in which a power supplying device connects with a vehicle, which has a power storage device to be supplied with power from the power supplying device, via a power supply wire (30, 31) and an earth wire to be used for supplying power and a control wire for transmitting a control signal to be used for power supply control of the power storage device, the vehicle comprising: a communication unit that sends and receives a communication signal, which is different from the control signal; and a vehicle side superimposition/separation unit that performs superimposition/separation of the communication signal in regard to the control wire and the earth wire, wherein the vehicle side superimposition/separation unit comprises a signal converter of an electromagnetic induction type having a primary coil, which is connected with at least one of the control wire and the earth wire, and a secondary coil, which is coupled electromagnetically with the primary coil and is connected with the communication unit, wherein the power supplying device comprises a power supplying device side superimposition/separation unit that performs superimposition/separation of the communication signal for communication via the control wire and the earth wire, characterised in that a ratio of winding number of the primary coil to winding number of the secondary coil is less than one in a system related to communication of the communication signal, having a characteristic that an influence of crosstalk due to a capacitive reactance component between the control wire and the earth wire, and the power supply wire (30, 31) is larger than an influence of crosstalk due to an inductive reactance component between the control wire and the earth wire, and the power supply wire (30, 31), wherein a ratio of winding number of the primary coil to winding number of the secondary coil is more than one in a system related to communication of the communication signal, having a characteristic that an influence of crosstalk due to a capacitive reactance component between the control wire and the earth wire, and the power supply wire (30, 31) is smaller than an influence of crosstalk due to an inductive reactance component between the control wire and the earth wire, and the power supply wire (30, 31). a communication unit that sends and receives a communication signal, which is different from the control signal; and a vehicle side superimposition/separation unit that performs superimposition/separation of the communication signal in regard to the control wire and the earth wire, wherein the vehicle side superimposition/separation unit comprises a signal converter of an electromagnetic induction type having a primary coil, which is connected with at least one of the control wire and the earth wire, and a secondary coil, which is coupled electromagnetically with the primary coil and is connected with the communication unit, wherein the power supplying device comprises a power supplying device side superimposition/separation unit that performs superimposition/separation of the communication signal for communication via the control wire and the earth wire, characterised in that a ratio of winding number of the primary coil to winding number of the secondary coil is less than one in a system related to communication of the communication signal, having a characteristic that an influence of crosstalk due to a capacitive reactance component between the control wire and the earth wire, and the power supply wire (30, 31) is larger than an influence of crosstalk due to an inductive reactance component between the control wire and the earth wire, and the power supply wire (30, 31), wherein a ratio of winding number of the primary coil to winding number of the secondary coil is more than one in a system related to communication of the communication signal, having a characteristic that an influence of crosstalk due to a capacitive reactance component between the control wire and the earth wire, and the power supply wire (30, 31) is smaller than an influence of crosstalk due to an inductive reactance component between the control wire and the earth wire, and the power supply wire (30, 31).