The electron microprobe has been used to analyze cross sections of ground layers which have been sampled from oil paintings produced by Japanese oil painters in the late 19th century. The ground has been classified into three types according to structure and materials. Type 1 has a three-layer construction which contains : 1) calcium carbonate layer; 2) calcium carbonate and lead white layer; 3) lead white layer from bottom layer upward. Fossils, calcareous nannoplankton, are observed in calcium carbonate in most of type 1 ground. Type 1 ground is characteristic in the works painted in Great Britain and Japan. It is similar to the ground of one of the Winsor and Newton canvases. Type II is characteristic in the works produced in Italy and France, and has a one- or two-layer construction which contains lead white and a small amount of calcium carbonate. Type III does not belong to the above two types, and contains zinc oxide white.