PURPOSE: To provide a carbon dioxide adsorbent container which can be exchanged easily, can prevent the generation of a clearance where a carbon dioxide does not exist at the inside in the operating condition, and can be formed simply.

CONSTITUTION: This carbon dioxide adsorbent container 710 of a respiration device for diving has an outer tube 720 whose one side end face is made in a sealed bottom face; an inner tube 730 which can be inserted through a bottom hole opened at the center of the sealed bottom face of the outer tube 720, and its one side end face is made in a sealed end face; and a lid 750 which can be inserted to the opening of the outer tube 720, in which an inserting hole to insert the front end of the inner tube 730 is formed. lid 750 is installed to the outer tube and the inner tube allowable to mount and demount, in the condition preventing its removal from the outer tube and the inner tube. This container 710 can be composed of three members having a simple structure formed separately, and the formation of the three members can be carried out also simply. The carbon dioxide adsorbent can be exchanged only by connecting and disconnecting the container to the respiration device.