This study aims at making a research into the physical and chemical properties of the neolithic era potterys, which are unearthed from Gosanli, Sagaeli, Bukchonli, Samyangdong and Gonaili districts in Cheju Island, by using X-ray diffraction, X-ray fluorescence spectrometer and Mossbauer spectroscopy. This results are as follows. The principal component of five plain coarse pottery sherds by X-ray fluorescence spectrometer and X-ray diffraction spectrum at the room temperature is silicate mineral which is equal to SiO$_2$, and they also have a little magetite, hematite and goethite. The most existent Fe is Fe$^$+3/ through Mossbauer spectroscopy analysis of plain coarse pottery sherds and it is presumed that the magnetic hyperfine splitting caused this result. The ratio of Fe$^$2+//(Fe$^$2+/+Fe$^$3+/) is mostly zero by Mossbauer spectrum at the room temperature of plain coarse pottery sherds and it is thought because they were fired in the atmosphere.