Abstract: A treatment subject receiving vessel body 72 comprises a portable vessel main body 92, a treatment subject support member 100 installed in the vessel main body and capable of supporting a plurality of treatment subjects W, a joint port 96 formed in one side surface of the vessel main body and communicating with the interior of the vessel main body, an openable/closable gate valve 94 installed in the joining port, and an exhaust port 108 made openable/closable to be capable of exhausting the vessel main body. When the gate valve and exhaust port are closed, the vessel main body is brought to the sealed state.