Ulcerative colitis (UC) is an inflammatory bowel disease. Indigo Naturalis/Qing Dai (QD) has been shown to ameliorate UC. Indigo (INDG) constitutes 42.4% of the QD. We have recently reported that INDG suppresses bleeding from the intestine and improves the colon histology. INDG is an aryl hydrocarbon receptor (AhR) ligand. In addition, activation of the AhR induces anti-inflammatory cytokines and suppresses intestinal inflammation. However, it remains to be elucidated whether the AhR-activation is involved in the intestinal epithelial wound healing. Here, we investigated the effects of QD and INDG on the activation of AhR and the epithelial wound healing. The activation of AhR was examined by the induction of Cytochrome P450 1A1 (CYP1A1), whose expression is known to be regulated by the AhR. QD and INDG induced CYP1A1 both in Caco-2 colon carcinoma cells and in the mouse colon. QD and INDG accelerated the wound closure in Caco-2 cells and these wound closures were inhibited by an AhR-antagonist. The orally administered INDG may suppress the epithelial loss and bleeding in the colon through the accelerated wound closure by the activation of AhR in the intestinal epithelium.