In today's fast‐paced environment, the downsizing of electronic devices has become imperative. A high driving frequency is effective for the downsizing of electronic equipment. However, one problem with high driving frequency is that it increases the ac resistance and heat generation on passive devices. Using a magnetic coating on the copper wire can effectively reduce the ac resistance. In this study, we propose a method for wrapping a magnetic tape around a copper wire to easily provide a uniform magnetic coating for reducing the ac resistance. In the magnetic field simulation, we reduced the proximity effect in the coil by using a magnetic tape. The temperature rise at the thermal saturation was reduced by 26% for the experiment with a high‐frequency current of 4 A. Applying the magnetic tape to a single‐wire coil effectively reduced the ac resistance and heat generation. © 2020 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.