NOVELTY - A fuel-cell built-in type hydrogen fermentation bioreactor has a device for supplying air (20) connected to an oxygen inhalation opening (12) of a fuel cell (10), and a bioreactor (1) having a gaseous-phase portion (2) which produces hydrogen gas by microorganism gatherings. A fuel flow path (22) connects the gaseous-phase portion of the bioreactor and a hydrogen inlet (11) of the fuel cell.    USE - For producing electricity.    ADVANTAGE - Since hydrogen produced from the bioreactor is supplied directly to the fuel cell, modification of a heating gas is not required and energy supplied for modification is also not required. Since reduction of hydrogen partial pressure of the gaseous-phase portion of the bioreactor is accelerated by the electricity generated from the fuel cell, high hydrogen producing efficiency is maintained in the bioreactor. The existing hydrogen fermentation bioreactor is used without modifications and the fuel cell is integrated to obtain the fuel-cell built-in type hydrogen fermentation bioreactor. The organic waste is treated effectively by using the methane-fermentation microorganism present in the bioreactor and thus the efficiency of waste water treatment is increased and also hydrogen producing efficiency is improved. Thus pollution is prevented. By using the hydrogen fermentation bioreactor, hydrogen as a source of energy is produced efficiently and stably and polluting of environment is prevented.    DETAILED DESCRIPTION - A fuel-cell built-in type hydrogen fermentation bioreactor has a device for supplying air which is connected to an oxygen inhalation opening of a fuel cell and a bioreactor having a gaseous-phase portion which produces hydrogen gas by microorganism gatherings. A fuel flow path connects the gaseous-phase portion of the bioreactor and a hydrogen inlet of the fuel cell. Oxygen (27) consumed according to electric-power load is supplied to the fuel cell by using the device for supplying air. Hydrogen gas is inhaled from the gas-phase portion of the bioreactor, and supplied to the fuel cell by reduction of hydrogen partial pressure of hydrogen inlet based on consumption of hydrogen gas (26) in the fuel cell.    DESCRIPTION OF DRAWING(S) - The figure shows the explanatory drawing of the fuel-cell built-in type hydrogen fermentation bioreactor. (Drawing includes non-English language text).    Bioreactor (1)    Gaseous-phase portion (2)    Fuel cell (10)    Hydrogen inlet (11)    Oxygen inhalation opening (12)    Device for supplying air (20)    Fuel flow path (22)    Desulfurizer (23)    Hydrogen gas (26)    Oxygen (27)