From experiments using colitis model mice, the present inventors discovered that siRNAs that suppress the CHST15 gene expression have a therapeutic effect against Crohn's disease or ulcerative colitis. Specifically, the present inventors discovered that the siRNAs which suppress the CHST15 gene expression can serve as an agent for promoting mucosal healing, in particular, an agent for treating Crohn's disease or ulcerative colitis, and thereby completed the present invention.本發明者係經由使用大腸炎模式小鼠的實驗，發現抑制CHST15基因表現的siRNA，對於克隆氏症或潰瘍性大腸炎顯現治療效果。亦即，發現抑制CHST15基因表現的siRNA為黏膜治癒促進劑，特別是成為克隆氏症或潰瘍性大腸炎的治療劑，本發明因而完成。
