To remove unnecessary laver leaves and other attached materials from a laver net in the case of withdrawing the laver net from the sea to a boat e.g. at the end of the culture season and to filter and collect the removed laver leaves and other attached materials on the boat without throwing the leaves, etc., into the sea.

A cylinder part 3 is placed on the upper part of a stand 1 in a state inclined at an inclination angle of 10° directing the laver net inlet port of the cylinder part downward and nozzles 4, 5, 6, 7 are attached to the cylinder part 3. A jet flow receiving part 8 is placed in contact with the laver net inlet port and is connected to a filtration apparatus 10 with a transfer hose (polyvinyl compound hose) 9. The laver net 11 holding unnecessary laver leaves and other attached materials is introduced into an opening above the jet stream receiving part 8 by the power of a winding roller 2 and washed with the jet flows of the nozzles 4, 5, 6, 7 while passing through the pipe 3. The laver leaves and other attached materials separated by the washing operation are transferred by the jet streams of the nozzles 4, 5, 6, 7 from the jet flow receiving part 8 to the filtration apparatus part 10 and filtered.