PURPOSE: To adsorb and collect uranium in seawater, by a method wherein an adsorption agent is held in a net-rope structure which is in the sea near the sea level, and the sea water passes through the adsorption agent due to the movement of the seawater.

CONSTITUTION: A cubical space is formed in the sea with net partitions in a net- rope structure which consists mainly of synthetic fiber rope and synthetic fiber net, and an adsorption agent is placed in the surrounding space to form an adsorption bed. Edges of the net structure consists of tension ropes and shape-holding materials. Floating objects 5 are located at adequate intervals, and sinking objects 6 are hung down corresponding to the objects 5 by means of ropes. A transverse tension is held by the use of mooring cable 7 and concrete block type anchors 8 positioned at corners of the net unit structure. The adsorption agent on the adsorption bed repeates the movement in accordance with the period of the wave to perform the adsorption of uranium. The adsorption agent which has adsorbed uranium in seawater is lifted onto a ship, and operations such as washing, desorption, and concentration of uranium are performed in a factory on land to collect the uranium.