A proximity switch device adapted to provide a contactless switching function for an electric device, such as a radio mounted in a vehicle when approached by an object, such as a driver's hand including a floating capacitance detector and an amplified oscillator circuit for converting a change in floating capacitance into a change in frequency signal, a voltage fluctuation detecting circuit for detecting an approach of the object based upon said frequency signal, and a flip-flop switch for switching on and off the electric device whenever an output signal indicating the approach of the object is produced.