To provide a virus plasmid and a vector system, since it is required to find out a virus which can be used as a plasmid vector capable of introducing a gene into the chromosome of a stationary cell and has high safety, and construct the vector system capable of being utilized for gene therapies using the virus.

This Supuma virinae plasmed has the following characteristics. (1) The plasmid has a core protein gene (gag), a protease/integrase/reverse transcriptase gene (pol), envelope protein gene (env), transactivator gene (bel I) and bel II between 5'-longterminal repeat(LTR) and 3'-LTR, and does not have bel III. (2) The 5'-LTR is 1,355 bp, and the 3'-LTR is 1,355 bp. (3) The gag is 1,545 bp. (4) The bel I is 630 bp, and the bel II is 942 bp.