A far infrared rays (FIR) substrate applied in electric device mainly includes an electric device and a FIR releasing material. The electric device is operated with electric power. The electric device emits an electromagnetic wave during operation wherein the electromagnetic wave is able to, according to Faraday law of electromagnetic induction, induce an induction electromotive force within the circuit of the electric device for emitting the electromagnetic wave outward the electric device which is able to be received by a human body. The FIR is transmitted by the electromagnetic wave to human body to generate absorption resonance by human body at 9.36 um wavelength, thus the human body is able to absorb the energy of the FIR releasing material. It is able to activate resonance of water molecular in human cells and activate metabolism.
