In case of reusing only existing piles other than foundation, it is necessary to select a demolition method of the foundation that doesn’t damage the piles. There is no study to examine the relation between the extent of the pile damage and the working efficiency in the demolition method. This paper describes the experiments of the relation using the foundations and the piles of building under demolition. The method with cutter is the most reasonable because its working efficiency is equivalent to the method with crusher and its effect on the pile soundness is equivalent to the method with wire-saw.
