Abstract: An EMI bead core filter is used to suppress or reduce a noise by utilitizing the characteristics of increasing the impedance in high frequency, which comprises of a ferrite core, a lead wire and a coating layer. The coating layer deposited on the upper portion of the core and the bending of the wire to adhere between the core and the wire by coating with an epoxy powder. A process of this invention comprises of the steps of bending, inserting, tapping, heating, coating, packaging and hardening, and especially the coating is accomplished by carrying repeatedly out four times, that is, upon preheating at 380.degree. C. and heating at 335.degree. to 340.degree. C. A coating apparatus has a vacuum device, a powder chamber and two heaters. The filter has a high impedance and a small size.