Metallic microstructure inspection is essential in assuring long-life operation of steam power stations. In common chemical etching methods for microstructure observation, the etching conditions are not readily specifiable and delicate handling techniques are required. To overcome this difficulty a physical etching method is employed with micro-sputtering technique where an inner-magnet is provided with a portable evacuation system and a movable power supply. A specimen taken from the main Y-shaped steam pipe of a disassembled power plant was etched using this new apparatus and a replica of the pipe surface was observed by optical microscopy. The result of observation was as good as that obtained by the chemical etching performed under the most favorable condition.