Iron oxides are very important coloring agents for porcelain decoration.By firing iron oxide powder with frits and glazes under oxidation and reduction atmospheres at 800 to 1300 ℃, iron oxide shows the diverse color changes such as red, yellow, tan, grey, salmon, ochre, orange, brown, light green, blue, and black.In this paper,the role of particle size and morphology of nanophase α-Fe2O3 particles of 30 to 160 nm in average diameter which were hydrothermally synthesized at 100 to 120 ℃ from some FeC13 solutions on the reddish color tone for overglaze decoration, and the role of Fe2+/Fe3+ state in celadon glaze and the role of α-Fe2O3 content in the porcelain body on the color of celadon were investigated.Furthermore, some activities of Saga Ceramic Research Laboratory and the history of ceramic ware technology in Arita (Saga Pref., Japan) will be introduced in this presentation.