A fuel cell system comprising: a fuel cell module for generating electrical energy by electrochemical reactions of a fuel gas and an oxygen-containing gas; a combustor for raising the temperature of the fuel cell module; a fuel gas supply apparatus for supplying the fuel gas to the fuel cell module; an oxygen-containing gas supply apparatus for supplying the oxygen-containing gas to the fuel cell module; a water supply apparatus for supplying water to the fuel cell module; a power converter for converting direct current electrical energy generated in the fuel cell module to electrical energy according to requirements specification, wherein the power converter is connected to a first wire; a control device for controlling the amount of electrical energy generated in the fuel cell module, wherein the control device is connected to a second wire; and a casing containing the fuel cell module, the combustor, the fuel gas supply apparatus, the oxygen-containing gas supply apparatus, the water supply apparatus, the power converter, and the control device, wherein the casing includes a casing body and an open/close door that opens/closes the casing body using a coupling member as a fulcrum point; and has a hinge for opening/closing the open/close door by rotation about a vertical axis or a horizontal axis through the hinge, characterized in that the power converter and the control device are attached onto the open/close door; and the fuel cell system comprises wire connectors (82, 86) including first connectors (82a, 86a) connected to the first and second wires (80, 84) of the power converter and the control device, respectively, and second connectors (82b, 86b) attached to the casing body, wherein the second connectors (82b, 86b) are detachably connected to the first connectors (82a, 86a); the wire connectors (82, 86) are provided adjacent to the axis of the hinge, and the open/close door is detachable from the casing body in a state where the power converter and the control device are attached onto the open/close door, and the first connectors (82a, 86a) are detached from the second connectors (82b, 86b). a fuel cell module for generating electrical energy by electrochemical reactions of a fuel gas and an oxygen-containing gas; a combustor for raising the temperature of the fuel cell module; a fuel gas supply apparatus for supplying the fuel gas to the fuel cell module; an oxygen-containing gas supply apparatus for supplying the oxygen-containing gas to the fuel cell module; a water supply apparatus for supplying water to the fuel cell module; a power converter for converting direct current electrical energy generated in the fuel cell module to electrical energy according to requirements specification, wherein the power converter is connected to a first wire; a control device for controlling the amount of electrical energy generated in the fuel cell module, wherein the control device is connected to a second wire; and a casing containing the fuel cell module, the combustor, the fuel gas supply apparatus, the oxygen-containing gas supply apparatus, the water supply apparatus, the power converter, and the control device, wherein the casing includes a casing body and an open/close door that opens/closes the casing body using a coupling member as a fulcrum point; and has a hinge for opening/closing the open/close door by rotation about a vertical axis or a horizontal axis through the hinge, characterized in that the power converter and the control device are attached onto the open/close door; and the fuel cell system comprises wire connectors (82, 86) including first connectors (82a, 86a) connected to the first and second wires (80, 84) of the power converter and the control device, respectively, and second connectors (82b, 86b) attached to the casing body, wherein the second connectors (82b, 86b) are detachably connected to the first connectors (82a, 86a); the wire connectors (82, 86) are provided adjacent to the axis of the hinge, and the open/close door is detachable from the casing body in a state where the power converter and the control device are attached onto the open/close door, and the first connectors (82a, 86a) are detached from the second connectors (82b, 86b).