The present invention has an object to provide an effective and safe therapeutic agent for inflammatory diseases such as sepsis, hepatitis, and inflammatory bowel disease, and solves the above object by providing a therapeutic agent for inflammatory diseases containing adenosine N1-oxide or a derivative thereof as an effective ingredient.本發明係以提供一種有效果且安全的敗血症、肝炎或發炎性腸疾病等發炎性疾病治療劑作為課題,其可由作為有效成分含有腺苷N1-氧化物或其衍生物所成的發炎性疾病治療劑解決。