A fuel cell assembly (1) is disclosed. The fuel cell assembly (1) has a fuel cell stack (2) formed by laminating a plurality of cells; plus and minus current extraction sections (4), the current extraction sections (4) extracting current generated by the fuel cell stack and sandwiching the fuel cell stack with respect to the direction of lamination; and a passage (4a) allowing flow of a fluid provided in at least one of the current extraction sections. Further a fuel cell system, which has the above fuel cell stack and a heating device (24, 26, 32, 90) for heating the passage for the fluid, is disclosed.