The crucibles of Baekje Kingdom from the Ssangbukri Site which were used for glass and metal melting had light brown, grayish blue and grayish brown colored bodies. In thin section, the crucibles contained numerous quartz grains and pottery fragments. The surface was covered with fine grained quartz for thermal resistance. Based on decomposition of mica group minerals and formation of mullite detected by X-ray diffraction analysis, it was inferred that all crucibles have been fired over 1,000℃. It was also found that firing temperature has exceeded 1,100℃ in some crucibles because feldspar was not detected. The maximum temperature was assumed at 1,200℃. The magnetic susceptibility values and geochemical characteristics sorted out the crucibles into two groups that differed from the characteristics of the local soils. This reflected geological setting of the site where the alluvium was formed from two kinds of surrounding rock masses, granite gneiss and biotite granite. However, the local soils had similarities with the crucibles in weatheringdegree and geochemical behavior of major elements. In consequence, it was considered that the raw clay of the crucibles was supplied from the local area of the site.