The objective of the present invention is to improve the system efficiency of the fuel cell generator that generates hydrogen by electrolyzing water and generates electricity using the generated hydrogen. For this purpose, a fuel cell generator, which includes a fuel cell for generating electricity using hydrogen, a electrolytic device for electrolyzing water using electricity from an external electricity system, and a hydrogen storage device for storing the hydrogen that has been generated by the electrolytic device and supplying the stored hydrogen to the fuel cell, is equipped with an heat supplying device for supplying the heat that has been generated in the fuel cell during the electricity generation to the electrolytic device. Alternatively, a fuel cell generator, which includes a fuel cell for generating electricity using hydrogen and electrolyzing water using electricity from an external electricity system, and a hydrogen storage device for storing the hydrogen that has been generated during the electrolysis and supplying the stored hydrogen to the fuel cell during the electricity generation, is equipped with an heat supplying device for storing the heat that has been generated during the electricity generation and supplying the stored heat to the fuel cell during the electrolysis.