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.
