To solve a problem of failing to lift a CB (channel box) piece in the case of alignment being shifted by several millimeters although only the completely aligned CB pieces are liftable in a device for taking out only one piece in good order by remote operation out of a box containing a plurality of CB pieces in the water.

An aligning mechanism pushes the CB piece by a positioning guide from the protruding side of V-shape cross section of the CB piece into the recessed side direction. Maintained in this state, the CB piece is moved into a specified position by another CB piece pressing cylinder. An oscillating suction pad and a sliding claw mechanism are added to a lifting mechanism to cover eccentricity of scores of millimeters. Particularly in a slide mechanism, the second CB piece serves as a reference stopper, so that one CB piece can be positively lifted by a claw.