A case of acute liver damage by ingestion of Aplysia kurodai, a sea hare is reported. A 40-year-old man, complaining of vomiting and pyrexia after eating a sea hare, was admitted. Laboratory data showed mild liver damage with sustained elevations of aminotransferases. Microscopic findings in the liver biopsy specimen revealed characteristic apoptotic hepatocytes accompanied by mitotic hepatocytes. It is suggested that bioactive substances in the sea hare might induce such apoptosis of hepatocytes in the liver.