NOVELTY - The system (10) has casing (26) divided into primary and secondary fluid supply sections (88a,88b), module section (90), and electrical equipment section (92) with power converter (22) and control device (24). The module section has fuel cell module (12) and combustor (14), arranged between primary fluid supply section and electrical equipment section. The secondary fluid supply section has oxygen-containing gas supply apparatus (18) arranged on lower surface of module section. The fuel and water supply apparatuses (16,20) are set in primary fluid supply section.    USE - Fuel cell system e.g. solid oxide fuel cell system mounted in vehicle. Can also be used in molten carbonate fuel cell system, phosphoric acid fuel cell system and hydrogen membrane fuel cell system.    ADVANTAGE - since the module section having fuel cell module and combustor, is arranged between primary fluid supply section and electrical equipment section, the respective components can be accessed from the front side for carrying out maintenance operation, so that the maintenance operation can be performed easily. The space in the casing is divided depending on the operating temperature and function so that diffusion of heat and fluid can be minimized, and the optimum layout can be achieved. The inhalation of fuel gas into the oxygen-containing gas supply apparatus can be prevented reliably. The cooling of the primary and secondary fluid supply sections and electrical equipment section can be facilitated. The position of the center of gravity of the entire fuel cell system can be lowered, so that entire fuel cell system can be installed more stably.    DESCRIPTION OF DRAWING(S) - The drawing shows a front view of the fuel cell system.    Fuel cell system (10)    Fuel cell module (12)    Combustor (14)    Fuel gas supply apparatus (16)    Oxygen-containing gas supply apparatus (18)    Water supply apparatus (20)    Power converter (22)    Control device (24)    Casing (26)    Primary fluid supply section (88a)    Secondary fluid supply section (88b)    Module section (90)    Electrical equipment section (92)