The present invention provides an antibody (anti-BAMBI antibody) which recognizes a polypeptide having the amino acid sequence of SEQ ID No: 1 or a polypeptide having an amino acid sequence containing deletion, substitution or addition of one or more amino acids as compared to the amino acid sequence of SEQ ID No: 1, a method for manufacturing same, a therapeutic agent for colon cancer or liver cancer comprising an anti-BAMBI antibody, a diagnostic agent comprising a primer or probe for detecting the BAMBI gene, and a therapeutic agent for colon cancer or liver cancer comprising a vector which generates BAMBI dsRNA, and the like.