A fuel cell device comprising: a reformer that reforms a raw material for power generation and generates a reformed gas; a fuel cell that generates electric power utilizing air for power generation and the reformed gas; a combustor that combusts both an off-gas of the reformed gas and an off-gas of the air for power generation discharged from the fuel cell, and generates a combustion exhaust gas which serves as a heat source of the reformer; a first air heat exchanger that has a combustion exhaust gas path through which the combustion exhaust gas flows and a first air supply path through which the air for power generation flows, and that heats the air for power generation by heat exchange between the combustion exhaust gas and the air for power generation; a fuel cell storage which stores the fuel cell, and through which the off-gas of the air for power generation discharged from the fuel cell and heading to the combustor flows; characterized in that a second air heat exchanger that has a second air supply path which supplies the air for power generation, which has flowed through the first air supply path, to the fuel cell, and that heats the air for power generation by heat exchange between the off-gas of the air for power generation which flows in the fuel cell storage and the air for power generation which flows through the second air supply path; and a housing that stores the reformer, the fuel cell, the combustor, the first air heat exchanger, the fuel cell storage, and the second air heat exchanger, wherein the first air supply path and the second air supply path are disposed to cover whole members stored in the housing. a reformer that reforms a raw material for power generation and generates a reformed gas; a fuel cell that generates electric power utilizing air for power generation and the reformed gas; a combustor that combusts both an off-gas of the reformed gas and an off-gas of the air for power generation discharged from the fuel cell, and generates a combustion exhaust gas which serves as a heat source of the reformer; a first air heat exchanger that has a combustion exhaust gas path through which the combustion exhaust gas flows and a first air supply path through which the air for power generation flows, and that heats the air for power generation by heat exchange between the combustion exhaust gas and the air for power generation; a fuel cell storage which stores the fuel cell, and through which the off-gas of the air for power generation discharged from the fuel cell and heading to the combustor flows; characterized in that a second air heat exchanger that has a second air supply path which supplies the air for power generation, which has flowed through the first air supply path, to the fuel cell, and that heats the air for power generation by heat exchange between the off-gas of the air for power generation which flows in the fuel cell storage and the air for power generation which flows through the second air supply path; and a housing that stores the reformer, the fuel cell, the combustor, the first air heat exchanger, the fuel cell storage, and the second air heat exchanger, wherein the first air supply path and the second air supply path are disposed to cover whole members stored in the housing.