a fuel cell includes a substrate layer , a first electrode , a second electrode , a first chamber layer and a second chamber layer , and all of which are integrally formed by co - firing . the substrate layer includes a first surface and a second surface opposite to the second surface , and the first electrode , the second electrode are formed on the first and second surfaces , respectively . the first chamber layer , disposed on the first electrode , includes a first flow passage and a first fuel chamber connected thereto , and a first gas passes the first flow passage , enters the first fuel chamber and contacts the first electrode . the second chamber , disposed on the second electrode , includes a second flow passage and a second fuel chamber connected thereto , and a second gas passes the second flow passage , enters the second fuel chamber and contacts the second electrode .