The present invention provides an agent for protecting the liver and/or promoting liver regeneration, which contains a heparin-binding EGF-like growth factor-like growth factor (HB-EGF) or a partial peptide thereof, or a nucleic acid that encodes same, and an agent for the prophylaxis or treatment of liver diseases. The present invention further provides a method for producing a cell for liver protection and/or promoting liver regeneration, and for the prophylaxis/treatment of a liver disease, which includes introducing a nucleic acid that encodes HB-EGF or a partial peptide thereof into a cell collected from an animal.