Provided are isolated collectin (CL-L2s) genes including a base sequence set out in SEQ ID NO: 1, 3, 5, 7, 9, 12, 36, 38 or 40 relating to a novel collectin which are expected to exhibit an antibacterial activity, an antiviral activity and the like particularly in a human body; and isolated collectin proteins including an amino acid sequence set out in SEQ ID NO: 2, 4, 6, 8, 10, 13, 37, 39 or 41 and derivatives and fragments thereof.