A holding device for removing wave-dissipating blocks using net chains was developed to reduce the operation risk. The device is simple and the operation is easy. It is capable to hold a thing with various shapes. It has been employed in several block removal works and its time and cost efficiency has been revealed.
　A hydrofoil of ship sank to seabed of western area in the Sea of Japan by an accident in 2007. Since the target area was as deep as the depth of 180m and the maritime condition was strong, the recovery by divers was impossible. Therefore, the holding device with net chain was applied.
　The horizontal position control seemed to be difficult due to the swing of device in water. However, it became to control the device position by a simple operation method of putting a part of the net chain on the sea bottom.
　From this result, it was proved that the device was applicable to recovery of the falling objects in deep sea.