A prophylactic and/or therapeutic agent for non-alcoholic fatty liver disease (NAFLD), in particular non-alcoholic steatohepatitis (NASH), said prophylactic and/or therapeutic agent comprising a concentrate of Japanese plum (Prunus mume) juice or a processed product thereof. The prophylactic and/or therapeutic agent, which is obtained with the use of ingredients contained in a plant or a processed product thereof, has a high safety and can be easily taken. It was confirmed that hepatic fibrosis can be ameliorated by orally administering a concentrate of Japanese plum juice or a processed product thereof to streptozocin (STZ)-induced NAFLD model mice and STZ-induced NASH model mice.一種包含梅果汁濃縮物或其處理物的非酒精性脂肪肝疾患（NAFLD），特別是非酒精性脂肪肝炎（NASH）的預防及/或治療劑，因為該預防及/或治療劑是利用植物所包含的成分或其處理物而獲得，所以安全且攝取容易。 將梅果汁的濃縮物或其處理物，對（STZ）誘發NAFLD模型小鼠或STZ誘發NASH模型小鼠口服給藥，確認可減輕肝纖維化。
