PURPOSE: To facilitate the burying operation of an anchor by forming a hole in a sand layer in utilizing a jet stream injected through a nozzle through a nozzle thereby to cause the anchor to deeply immerse into a sand layer.

CONSTITUTION: A pump 2 is suspended from a working ship 1, and the pump 2 is connected to an insertion pipe 3 through a flexible hose 6. Further, a high-pressure pump 8 loaded on a ship is connected to a nozzle part 9, and a high-speed jet stream can be injected from this part 9. Accordingly, a jet stream is injected through the nozzle part 9 to form a hole in the sand layer, and floating sand is sucked up by means of the pump 2 through the flexible hose 6, whereby the anchor 1 is buried deeply into the sand layer. When the anchor 1 reaches a predetermined depth, the inserted pipe 3 and the like are withdrawn, and the anchoring cable of the anchor 1 is pulled thereby to position the anchor 1 laterally in the sand layer.