Device and method for inverting lining material

An inversion vessel 1 which: has an opening section 50 located in the lower section thereof and provided with an opening through which it is possible for a lining material to pass 20; and is equipped with an inversion nozzle 4 in the upper section thereof which is filled with a liquid 26. The liquid discharged into a liquid tank 28 from the opening section as a result of the action of a compressed gas for inverting the lining material is returned to the inversion vessel by a pump 42, and the lining material is continuously inverted. The opening section is provided with a sealing member 83 having an opening formed therein through which the lining material passes, and is provided with a sealing valve 92 which is displaced as a result of the fluid pressure of the liquid discharged from the sealing member. When a small-diameter attachment tool connected to the terminal end of the lining material passes through the sealing member, the discharge flow of the liquid from the sealing member increases, the sealing valv