The present invention proposes a circulation fuel cell which can generate electricity at high efficiency by circulating fuel and an oxidizing agent in an environment in which air cannot be sucked. The circulation fuel cell comprises: a plurality of stacks which are selectively operated in a flow-through mode adapted to receive fuel and an oxidizing agent from a fuel supply unit and an oxidizing agent supply unit and to discharge an un-reacted material and a product and in a non flow-through mode adapted to receive the fuel and oxidizing agent discharged from one or more stacks operating in the flow-through mode and not to discharge an un-reacted material and a product; a plurality of pipe lines which are connected to the fuel supply unit and the oxidizing agent supply unit to supply the fuel and the oxidizing agent to the stacks and are connected to the stacks to form closed circuits; and switching devices which are installed on the pipe lines and open or close at least some of the pipe lines in response to a preset signal so that an un-reacted material accumulated in one or more stacks having operated in the non flow-through mode is supplied to one or more stacks having operated in the flow-through mode by switching operating mode of the stacks.
