A new noise suppressor made from metal-coated nonwoven fabrics is developed and studied by electromagnetic simulation and measurements. In the case of far fields, the shielding effectiveness to plane waves can be calculated using sheet resistance by regarding the non-woven fabric as a continuous metal sheet. Therefore, we show that the low wave impedance in the fine fiber layers generates a high shielding effectiveness. In the case of near fields, conductive noise suppression in a Microstrip line (MSL) with the non-woven fabric and with a continuous conductor is measured. Consequently, we clarify that there are some cases wherein the loss in the MSL while using the non-woven fabric is greater than that while using a continuous conductor in a specific frequency range. In this measurement, the loss from a noise suppression sheet (NSS) was 16% higher than that from a continuous film. From these results, we have successfully demonstrated the higher conductive noise suppression performance of the proposed thin, light, and flexible NSS.