PURPOSE: To damp vibrations at the time of force feed at a high place by connecting a rubber hose pipe at the front end of a piping material buried into a concrete structure body, forming a hole on its midway of the piping material and placing concrete while closing the hole in conformity with the height of placing.

CONSTITUTION: A piping material 8 is buried into a concrete structure body 7, and a bend 11 is connected to the front end of a projection from old concrete 9A. The bend 11 is connected through a swivel joint 10 at that time, and a rubber hose pipe 12 is bonded at a front end. A concrete pump car is arranged and joined at the lower end of the piping material 8, and concrete is force-fed by the piping material 8 and discharged from the front end of the rubber hose pipe 12. When concrete having excellent fluidity is placed, the bend 11 is removed from the swivel joint 10, and concrete can be executed. A dischargeable hole for concrete is formed on its midway of the piping material 8, and concrete is discharged and placed gradually from an open section while the hole is covered and closed in conformity with the height of placing.