A fuel cell system having a fuel cell which performs a power generation operation with fuel for power generation of a fuel container; a water supply control section which extracts water from the fuel container and supplies the water to the fuel cell before the fuel cell performs the power generation operation. A wet state of an electrolyte membrane in the fuel cell body is adequately maintained during system start-up (upon commencement of a power generation operation) and an electrochemical reaction related to the power generation operation is accelerated. In this manner, the fuel cell system which can adequately extract predetermined electrical energy and a fuel container for power generation applicable to that fuel cell system are provided.