The invention provides a storage device for transplanted seaweed. The device comprises a lower bottom plate and a top cover plate, wherein the lower bottom plate and the top cover plate are connected through four upright posts, and through holes are formed on the surface of the top cover plate. The device is characterized in that four upper vertical plates connected with the top cover plate and four lower vertical plates connected with the lower bottom plate are arranged among the upright posts respectively; meshes are arranged between the upper vertical plates and the corresponding lower vertical plates; and a gas bag with gas inflation and exhaust valves is fixed under the top cover plate. The gas bag is inflated by compressed air carried by a diver so that the device rises, or the gas bag is deflated to ensure that the device keeps neutral equilibrium or the device is sunk to facilitate transportation. Seawater in the lower vertical plates is pumped to the through holes on the top cover plate by a water pump and then sprayed downwards to form circulation, so that the seaweed leaves accumulated on the lower bottom plate can keep wet. The storage device has simple structure, low cost and firmness and durability, is convenient to use, saves time for taking and placing the seaweed, greatly reduces the cost for seaweed transplantation and improves the efficiency for collecting and planting the seaweed and the survival rate of the transplanted seaweed.