PROBLEM TO BE SOLVED: To provide an oscillator, a transmitting device, a rectifier, a rectifying device, a receiver, a receiving device and a transceiver capable of being miniaturized.SOLUTION: An oscillator comprises: an oscillation part whose threshold magnetic field for starting the oscillation, is more than zero; a conductor connected to the oscillation part in series; and a magnetic field application means for applying a first magnetic field to the oscillation part. The oscillation part and the conductor are arranged so that a second magnetic field generated by the current flowing into the conductor, is applied to the oscillation part, and the first magnetic field is smaller than the threshold magnetic field and a composite magnetic field of the first magnetic field and the second magnetic field is larger than the threshold magnetic field.
