To provide an installation structure of a storage container with radioactive cesium adsorbent excellent in workability, capable of efficiently adsorbing and collecting radioactive cesium, and taking measures to prevent theft.

A storage container 1 with radioactive cesium adsorbent includes: a metal storage container 2 forming a cage shaped container of which openings are covered with net like bodies 2b or porous plates, except a part, left as an input port 20, of openings existing on an outer peripheral surface of a three dimensional structure 2a structured of a frame 22, and having an opening/closing lid 25 attached to a frame part 22a around the input port 20 so as to be openable/closable; solid radioactive cesium adsorbent 3 made up of fibrous bodies or granular bodies, and packed from the input port 20 into the storage container 2; and a protruding member 26 formed on the frame 22 of the storage container 2 so as to protrude outward. There is provided a sticking out member 5 for sticking out into a flow path 40 from a path wall 41 forming the flow path 40, the sticking out member 5 and the protruding member 26 are connected and fixed to each other, and thereby the storage container 1 with radioactive cesium adsorbent of which the opening/closing lid 25 is closed and which is made to be in a lock state is placed in the flow path 40.