A fuel battery and a fuel cell stack, the fuel battery including: a fuel cell that generates electric power through a power generating reaction of reactant gases and includes a solid electrolyte layer having a first main surface and a second main surface, a first electrode disposed on the first main surface and serving as one of a cathode and an anode, and a second electrode disposed on the second main surface and serving as the other one of the cathode and the anode; an interconnector disposed so as to face the first electrode; and a current collecting member that electrically connects the first electrode to the interconnector. The first electrode includes: an inner portion connected to the current collecting member; and an outer portion disposed outward of the current collecting member and having a height larger than the height of the inner portion.