PURPOSE: To eliminate a material containing fine substance such as asbestos with safety and high efficiency, by sucking and removing under reduced pressure an object to be treated in a substantially hermetically sealed system by the use of liquid for treatment, and recovering such an object together with the liquid by suction under reduced pressure.

CONSTITUTION: A recovery head 1 is applied to a material such as a structural wall containing fine substance such as asbestos or rockwool, and water containing lubricant is supplied to a jet nozzle 3 from a water tank 6. Then the water is ejected under high pressure to moisten an object to be treated. Simultaneously, a decompression suction pump 9 is actuated to reduce the pressure of a safety tank 15 and a recovery tank 13, and the material moistened and peeled apart by pressurized water is sucked and recovered into a recovery bag 14 in a recovery tank 13 together with jet water. At the same time, water is separated and the separated water is returned to the water tank 6 through the safety tank 15 and a venturi 10. After this, the recovery head 1 is sequentially moved to repeat the operation. Thus the whole treatment can be performed with safety.