To reduce an execution cost by using as a bearing layer a stratum suitable for the use load of a press fitting bearing pile obtained by ground improvement, to enhance the reliability of the support pile by obtaining the characteristics of the support pile based on an actual measured value, with reduction in wastes occurred due to raised safety ratio.

The press fitting support pile 1 is press fitted while reducing the friction resistance applied to the support pile 1, and the bearing force caused by the friction resistance is estimated to correctly estimate the characteristics of the support pile 1 based on the bearing force of the stratum at the tip end of the support pile 1. The addition and release of a static load is repeated to the support pile 1 till the vertical displacement of the pile 1 is lowered down to less than a prescribed displacement amount, making the stratum at the tip end of the support pile 1 substantially elastic and also making the change in the static load and the vertical displacement quantity of the support pile 1 a proportional relation to obtain the characteristics of the support pile 1 for evaluation based on the relation. The support pile 1 is designed, after obtaining and estimating the characteristics as the press fitting support pile using an estimate pile 2, to constitute the press fitting support pile suitable for the stratum state and an upper structure.