The pigments used on the paintings of the proto-historic tombs in the western and eastern parts of Japan, and those in the Takamatsuzuka tomb, Nara Prefecture (central Japan) are described. Deterioration observed on the paintings in these tombs was studied. The ground layer used on Japanese tumulus paintings differs from that used in Korean and Chinese tumulus paintings. Lime plaster was common in Korea and China, whereas in Japan there was usually no ground coating. The isotope ratios of lead contained in the lime plaster of the Takamatsuzuka tomb were determined; these isotope ratios differed from Japanese and Chinese lead.