Abstract: [Problem] To provide a substance and method that are capable of effectively inducing proliferation of Faecalibacterium, thereby contributing to the prevention and treatment of diseases such as intestinal inflammation. [Solution] A proliferative agent for Faecalibacterium, comprising 1-kestose as an active ingredient. In accordance with the present invention, proliferation of Faecalibacterium can be effectively induced both in vitro and in vivo. In particular, it is possible to simply and effectively increase in vivo proliferation of Faecalibacterium in humans and animals, with almost no concerns regarding side effects or safety. It is also possible to prevent or treat intestinal inflammation by increasing in vivo proliferation of Faecalibacterium in humans and animals.