To reduce the outer size of an active carbon tower and its weight without impairing the effect of an active carbon container by inserting the bottom of the container to its upper part of which a freely detachable cover is provided into the inside a sealing material of a base box.

A bottom part of an active carbon container 12 wherein a freely detachable cover 3 is provided to its upper part is inserted into a base box 20 wherein a circular hole 10 is provided at a control part of an upper surface, and a ring-like seal 1 comprising an elastic body having a less inner diameter than the diameter of the circular hole 10 is provided along its inner periphery. A port 6b is provided to the active carbon container 12, and active carbon 30 is filled inside the active carbon container 12 while an appropriate space is left upward. A port 6a is provided to the base box 20. Then, a fluid flowing inside the base box 20 from the port 6a flows inside the active carbon container 12 from many holes provided to the bottom of the active carbon container 12, and after passing through the active carbon 30, flows out from a port 6b.