The authors forecasted perspective amounts of wastes coming from building demolition in three particular regions : Fukuoka Prefecture, Tokyo Metropolitan and Tottori-Shimane Prefectures. One of the most important points in the procedure is to identify the Failure Distribution Functions (FDF) of the building lifetime, which can be drawn from the Reliability Theory. The FDF is requisite in case of precise estimation of the demolished building floor area in a certain region. Then, we based on the public statistical data that the local government established in necessity of the property tax related affairs. Finally, following conclusions were obtained. The lifetime of wooden construction increases with the decrease of population density in the regions. It is observed that the lifetime of wooden construction in the areas having over 3000 persons per square meter is nearly 40 years. Whereas, the lifetime of other constructions does not recognized any significant relations to the population density. A measure to make building's lifetime long implies remarkable effect on a decrement of the demolition wastes. The crumbled concrete chunk accounts for over 50% of the entire wastes from demolished buildings, while the mixed waste reaches to 75 to 80% of all final disposal.