To provide a method for treating infectious organic waste, by which donated and non-used blood can be recycled without incinerating and the treatment cost can be significantly reduced as compared to conventional incineration treatment.

This method aims to treat infectious organic waste including waste blood, waste serum, waste plasma, body fluid, and gauze, absorbent cotton or the like with deposition of the above waste and the method includes the following steps. The steps are a water content controlling step (S1) to mix the infectious organic waste with organic waste such as kitchen waste and sawdust and to control the total water content to 30 to 60%, a mixing step (S2) to add a fermentation accelerator with seeded microorganisms to the mixture of the infectious organic waste and organic waste having the controlled water content and to mix, and a fermentation step (S3) to ferment the mixture of the infectious organic waste and organic waste with microorganisms.