The present invention provides a therapeutic agent for epithelial and endothelial injury, and in particular, for epithelial and endothelial microinjury, and the like. The therapeutic agent according to the present invention comprises, for example, a peptide of the following (a), (b), etc., a derivative thereof, or their salt: (a) a peptide comprising the amino acid sequence shown in any one of SEQ ID NOS: 10, 4, 12 and 6; or (b) a peptide comprising the amino acid sequence shown in any one of SEQ ID NOS: 16, 18, 20 and 22.