[Problem] The purpose of the present invention is to provide an indigestible substance that makes it possible to deliver probiotics to the distal colon and that has an exceptional effect for improving the intestinal environment, and a method for manufacturing the indigestible substance. [Solution] The present invention provides a method for manufacturing an indigestible substance, the method including: a step for preparing a mixture that contains dietary fiber, spore-forming bacteria and/or spores thereof, a sugar, and a protein or an amino acid; and a step for heating the mixture to form melanoidin. This makes it possible to provide an indigestible substance that makes it possible to improve bowel movement and promote proper defecation, and to prevent repeated diarrhea and constipation seen in irritable bowel syndrome through continual ingestion.
