The present invention is intended to provide a novel agent useful as atherapeutic or prophylactic agent for cachexia, which is a systemic syndromehavingmajor symptoms such as remarkable body weight loss, anemia, edema, anorexia,general prostration, malaise and the like in chronic diseases such asmalignant tumor,tuberculosis, diabetes, blood diseases, endocrine disorders, infections,acquiredimmunodeficiency syndrome, etc. The present invention provides a therapeuticorprophylactic agent for cachexia comprising as an effective ingredient acompoundhaving a specified morphinan skeleton represented by a compound of thefollowingstructure:(see formula 1)or a pharmacologically acceptable acid addition salt thereof.