In the removing work of wave-dissipating concrete blocks placed in harbors and the shore, the worker or the diver has been done the wire multiplication to the space of them generally.
　But, the staging is an unstable, and it is dangerous work.
　Therefore, a block transfer device with net chain was designed, the model device was produced, and the transfer experiment was done until now.
　In this research, the transfer experiment of blocks out of sight and block transfer work ware executed using block transfer device with net chain.
　Moreover, the lifting experiment of the models of various forms other than a block was tried.
　As a result,
・In the model experiment under out of sight, the time efficiency by improving of the operating method was 145 seconds/piece and that by improving device was 93 seconds/piece, while the time efficiency in sight was 75 seconds/piece.
・In transfer work of the underwater block in sight, the time efficiency of this device was 5 minutes/ piece that was better than 6.1 minutes /piece of the conventional method by divers.
・ By arranging the work condition suitable for the characteristic of this equipment, working time efficiency in sight situation will become about 3 minutes /piece, that out of sight situation will become
about 4 - 6 minutes/piece, and the transfer cost for a block will become about 1/3 of the conventional human power method of work of a for,.
・ This equipment can be expected applying also to the block buried in the sea bed, and object recovery of various form.