It is intended to provide a virus vector by which an exogenous nucleotide sequence can be inserted and easily transferred into a mammalian host cell and a gene encoded by the exogenous nucleotide sequence can be expressed in the host cell, and which has a low risk of pathogenicity and is appropriately usable in gene therapy of mammals. Namely, a recombinant vector originating in HHV-6 which has an exogenous nucleotide sequence in a portion corresponding to at least one region selected from the group consisting of U2, U3, U4, U5, U6, U7, U8, U24, and U25 regions of HHV-6; or a recombinant vector originating in HHV-7 which has an exogenous nucleotide sequence in a portion corresponding to at least one region selected from the group consisting of U2, U3, U4, U7, U8, U24, U24a, and U25 regions of HHV-7.