To provide a method and device capable of efficiently performing press-in of a support pile by a small amount of ground excavation, firmly performing the attachment of a reaction force removal jig during press-in, and working-efficiently performing the connection of the support pile and foundation after press-in completion.

An excavation hole 17 is excavated in a ground 1 along the side of foundation 3. A lower reaction force removal jig 4 having a bracket 8 receiving the lower face of the foundation is attached to the side lower part of the foundation 3. An upper reaction force removal jig 5 is attached to the foundation by being connected to the jig 4. A support pile 2 is pressed in by a hydraulic jack 15 supported on the upper reaction force removal jig 5. Ground reaction force is obtained by a plurality of the pressed-in support piles 2, and the foundation 3 is lifted by the hydraulic jack 15 to perform horizontal repair. Thereafter, the support pile 2 is connected to the lower reaction force removal jig 4, and the upper reaction force removal jig 5 is removed from the foundation 3. Concrete 23 is placed in the excavation hole 17, and the lower reaction force removal jig 4 and the support pile 2 are integrally fixed with the foundation 3.