Abstract: The present invention comprises a method of coating outside surface of a cylindrical member, with one end being closed and the other end being left open, which comprises dipping said member in a coating material, while holding the same substantially vertically and with the closed end being turned upward, characterized in that detecting the increase in the internal pressure caused by the evaporation of solvent of said coating material in an internal hollow part of said member, and releasing a part of the gas from said internal hollow part to prevent generating bubbles therefrom into the coating material.