NOVELTY - A fuel cell module (10) comprises fuel cell stack (28) formed by stacking fuel cells (26), each formed by stacking electrolyte electrode assembly (22) and separator (24); heat exchanger (30) for heating oxygen-containing gas; evaporator (32) for producing mixed fuel of raw fuel containing hydrocarbon and water vapor; reformer (34) for producing reformed gas; and combustor (36) for heating fuel cell stack, heat exchanger, evaporator and reformer. The module is surrounded by heat insulating layers (70, 72) which include inner and outer heat insulating layers.    USE - A fuel cell module, e.g. solid oxide fuel cell (SOFC) module, for generating electrical energy in power generation by electrochemical reactions of fuel gas (i.e., hydrogen gas) and oxygen-containing gas (i.e., air).    ADVANTAGE - The module prevents heat from excessively released from heat generating portion; thus reducing heat insulating capacity and production cost, facilitating thermally self-sustained operation, and improving heat efficiency.    DETAILED DESCRIPTION - Fuel cell module (10) comprises fuel cell stack (28) formed by stacking fuel cells (26), each formed by stacking electrolyte electrode assembly (22) and separator (24), where assembly includes anode and cathode with electrolyte interposed in between; heat exchanger (30) for heating oxygen-containing gas before supplying to fuel cell stack; evaporator (32) for producing mixed fuel of raw fuel containing hydrocarbon and water vapor obtained by evaporating water; reformer (34) for producing reformed gas by reforming mixed fuel; and combustor (36) for heating fuel cell stack, heat exchanger, evaporator and reformer. The module is surrounded by heat insulating layers (70, 72) which include inner and outer heat insulating layers. The inner heat insulating layer contains large amount of metal component in comparison with outer heat insulating layer.    DESCRIPTION OF DRAWING(S) - The drawing is a cross-sectional view of fuel cell module.    Fuel cell module (10)    Electrolyte electrode assembly (22)    Separator (24)    Fuel cells (26)    Fuel cell stack (28)    Heat exchanger (30)    Evaporator (32)    Reformer (34)    Combustor (36)    Heat insulating layers (70, 72)