A non-contact power supply transmitter system 100 transmitting an electric power from a transmitting device (TX) 200 to a receiving device (RX) 300 with a non-contact power supply transmitter method, the TX 200 including: a transmitting coil 202; a driver 204 causing the transmitting coil to generate a power signal of the electromagnetic field; and an FSK modulation unit 240 transmitting an FSK signal Sf through the transmitting coil, the RX 300 including: a receiving coil 302; a rectifier circuit 320 rectifying an electric current induced by the receiving coil; an FSK demodulation unit 340 demodulating the FSK signal received through the receiving coil; and a controller 312 controlling so that a rectifying mode of the rectifier circuit is switched to a diode rectifying mode during the FSK communication. The non-contact power supply transmitter system 100 and the RX 300 can execute a stable FSK communication.