To minimize the addition of new equipment and surely recover solid waste by opening solid waste container in pool water with an opening means and moving the exposed solid waste to a shield vessel and sealing it.

A manipulator 3 and an opening means 4 are fixed to a lifting means 2 for a cask 1, which is hung down in a pool W. By operating the manipulator 3, the opening means 4 is made to have access to solid waste container P and a lid or the vicinity of the lid is cut to expose in water the solid waste D contained in the solid waste container P. Next, by using the hoist 31 of the manipulator 3, another shield vessel S is hung down. Then, with the operation of the manipulator 3, the solid waste D is made upward posture and grasped with the manipulator 3 to charge in the shield vessel S. In place of the manipulator 3, a lid tightening means 5 is hung down, a lid is put on the shield vessel S to be in a sealed state, which is lifted up simultaneously with the lid tightening means 5 and contained in the hollow part in the cask 1. This cask 1 is run and carried out.