In this study, firing temperature of bricks from the Songsanri tomb complex is interpreted based on the mineralogical and physical changes of soil samples fired at different temperature. When soil samples were burned at 500 to 1,200 ℃, phase transition of clay minerals affected the mineralogical composition and microstructure, which leaded to alteration of physical features as color, water absorption and porosity. Mineralogical composition can be assumed to vary with the temperature by mineral phase stability, however, color, water absorption, porosity and microstructure had slow change under 1,000 ℃, and had rapid change from 1,000 to 1200 ℃. Upon the mineral and physical alteration of soil, firing temperature of bricks from the Songsanri tomb complex were estimated. Some bricks were over fired at temperature more than 1,200 ℃, some high-burned bricks were fired from 1,100 to 1,200 ℃, some bricks were fired by 900 to 1,000 ℃ and some bricks ere assumed not to be fired. Henceforward mineralogical and physical study can be applied to interpretate more precise firing temperature.