To facilitate pile pulling-out work by attaching a pipe for high pressure water injection provided additionally on one side of a seat pile with a short casing and a wire for isolation like a lariat in a lower end part of the casing attached to a lower part of the seat pile with the short casing by a holding member and performing isolation work of the ground around a peripheral wall of the pile and the ground in a pile lower part by injection of high pressure water and pulling up the wire for cutting fringe.

A wire for hoisting the pile and the wire for isolation like a lariat are provided by a plurality of holding members in an upper end part and a lower end part of the seat pile with the short casing to which the short casing made of a steel pipe and having larger diameter than diameter of an existing pile to be pulled out by about 10 cm, respectively, in a tip part of the seat pile. The pipe for high pressure water is additionally provided on one side of the seat pile.