The authors investigated a verdigris-colored copper plate (sample A) and a brown-red copper plate (Sample B) taken from the roof of the Hyokeikan, a building in the Tokyo National Museum which was built in 1901, using a scanning electron microscope and x-ray microanalyzer. The rust and deposits on the surface of Sample A were about 40mu thick and consisted mainly of copper and oxygen with small amounts of iron and sulfur. Surface deposits of sample B were 110mu thick and contained a greater amount of iron and phosphorus in addition to copper and oxygen. From the above results, the brown-red color of sample B was concluded to be due to the adherence of iron layers on the verdigris surface of the copper plate. Also discussed are possible sources of the contaminants iron and phosphorus.