A wireless power supply system is provided to include a headset and a vehicle-side system. The headset, which is attached to a head of a driver of a vehicle, is configured (i) to generate an electric power by using a received electromagnetic wave, (ii) to actuate a sensor with the generated electric power to measure an activity of the driver, and (iii) to transmit activity measurement data indicating a measurement result. The vehicle-side system, which is provided to the vehicle, is configured (i) to transmit the electromagnetic wave, (ii) to receive the activity measurement data from the headset, and (iii) to monitor the activity of the driver based on the received measurement data. The transmitting or receiving state of the electromagnetic wave is monitored to provide a monitoring result, which is to be notified.
