Objective of this research is recognition of weathering priority among red soils in center and south Japan and also searching the existence relationships between weathering conditions of soils and their iron oxides content. Hence Ishigaki Island (Okinawa prefecture), Hamamatsu and Iride (Shizuoka prefecture) were selected as sampling sites, where majority of soils were red and yellow ones. To quantify weathering characteristics of the samples, Productivity (SiO2)/(Al2O3+SiO2+FeO2+TiO2) and Parker (Na/0.35)+(Mg/0.9)+(K/0.25)+(Ca/0.7) indexes were applied and the mentioned elemental analysis was conducted through x-ray fluorescence spectroscopy (XRF). Also, quantities of two ubiquitous iron oxides (hematite and goethite) were used to make a comparison with the weathering indexes. Quantity of the two iron oxides was obtained through x-ray diffraction (XRD) and chemical measurements (Helmoren procedure _Fed_ and Acid Oxalate extractable iron _Feo_ methods, ISIRC, 1993). According to the results, more progress in weathering process is observed for Shizuoka samples.
