A used disposable diaper recycling system, comprising: a processing apparatus for producing processed waste, from used disposable diapers serving as a raw material, the processed waste having a predetermined water content and a volume reduced to a predetermined level; and a recovering facility (70, 90) for re-utilising the used disposable diapers by burning the processed waste as a fuel and recovering thermal energy; wherein the processing apparatus comprises: a processing bath; shredding means for shredding used disposable diapers and stirring the shredded disposable diapers together with a fermentative bacterium; and heating means for heating the shredded disposable diapers so as to regulate their water content to a predetermined level, and performing sterilisation through heating for a predetermined period of time, characterized in that the heating means is configured so that the shredded disposable diapers are controlled by a first heating temperature for heating the processing bath for promoting the activity of fermentative bacteria during fermentation and drying the shredded disposable diapers, to thereby yield a fermented product, and by a second heating temperature for sterilizing the fermented product in the processing bath, and evaporating water remaining in the fermented product, to thereby yield the processed waste, so that the processing apparatus is adapted to convert the used disposable diapers fed to the apparatus into the processed waste which has a water content of 5 % and a volume 1/3 that of the used disposable diapers, thereby realizing reduction in the amount of CO 2 emission, as compared with the case where the used disposable diapers are burned as they are. a processing apparatus for producing processed waste, from used disposable diapers serving as a raw material, the processed waste having a predetermined water content and a volume reduced to a predetermined level; and a recovering facility (70, 90) for re-utilising the used disposable diapers by burning the processed waste as a fuel and recovering thermal energy; wherein the processing apparatus comprises: a processing bath; shredding means for shredding used disposable diapers and stirring the shredded disposable diapers together with a fermentative bacterium; and heating means for heating the shredded disposable diapers so as to regulate their water content to a predetermined level, and performing sterilisation through heating for a predetermined period of time, characterized in that the heating means is configured so that the shredded disposable diapers are controlled by a first heating temperature for heating the processing bath for promoting the activity of fermentative bacteria during fermentation and drying the shredded disposable diapers, to thereby yield a fermented product, and by a second heating temperature for sterilizing the fermented product in the processing bath, and evaporating water remaining in the fermented product, to thereby yield the processed waste, so that the processing apparatus is adapted to convert the used disposable diapers fed to the apparatus into the processed waste which has a water content of 5 % and a volume 1/3 that of the used disposable diapers, thereby realizing reduction in the amount of CO 2 emission, as compared with the case where the used disposable diapers are burned as they are. a processing bath; shredding means for shredding used disposable diapers and stirring the shredded disposable diapers together with a fermentative bacterium; and heating means for heating the shredded disposable diapers so as to regulate their water content to a predetermined level, and performing sterilisation through heating for a predetermined period of time, characterized in that the heating means is configured so that the shredded disposable diapers are controlled by a first heating temperature for heating the processing bath for promoting the activity of fermentative bacteria during fermentation and drying the shredded disposable diapers, to thereby yield a fermented product, and by a second heating temperature for sterilizing the fermented product in the processing bath, and evaporating water remaining in the fermented product, to thereby yield the processed waste, so that the processing apparatus is adapted to convert the used disposable diapers fed to the apparatus into the processed waste which has a water content of 5 % and a volume 1/3 that of the used disposable diapers, thereby realizing reduction in the amount of CO 2 emission, as compared with the case where the used disposable diapers are burned as they are.