Abstract: This invention provides a fuel cell device which is simple in structure and easy to detect a fuel residual amount and includes a fuel tank accommodating a plurality of hydrogen storage alloys having mutually different hydrogen desorbing characteristics, a power generating section that uses the hydrogen desorbed from the fuel tank to generate electric power, a pressure sensor that detects a pressure of the hydrogen supplied into the power generating section, and an output circuit that produces a pressure variation detected by the pressure sensor.