Provided is a lentiviral vector system which sustains a high-frequency retrograde transportation ability in animal brain and has a higher titer. A kit for preparing a retrograde transport viral vector, which comprises: (1) a packaging plasmid containing the gag gene and pol gene of HIV-1; (2) a packaging plasmid containing an accessory gene of HIV-1; (3) a transfer plasmid containing a target gene; and (4) an envelope plasmid containing, as an envelope gene, a gene encoding a fused polypeptide comprising the extracellular domain of rabies virus glycoprotein (RV-G), the transmembrane domain of rabies virus glycoprotein (RV-G) or vesicular stomatitis virus glycoprotein (VSV-G) and the intracellular domain of vesicular stomatitis virus glycoprotein (VSV-G).