A composition, an Nrf2 activating agent, and a food according to the present invention comprise isohumulones or isomerized hop extract as an active ingredient. They are useful in treating, preventing, or ameliorating a disease of condition which is treatable, preventable, or ameliorable by the activation of transcription factor Nrf2. More specifically, the composition, the Nrf2 activating agent and the food according to the present invention are useful in treating, preventing, ameliorating, or alleviating chronic diseases which are believed to be caused or exacerbated by cellular damages due to oxidative stress in the body or environmental substances (for example, arteriosclerosis, hypertension, diabetes, cerebral nerve degenerative diseases, skin diseases, eye diseases, asthma, and cancer) or delaying progress of these diseases, or in detoxificating xenobiotic substances.