In the present invention, in order to expand the range of drug resistance markers available for use in a transgenic vector for animal cells, an expression vector comprising a multicloning site identical to those of the existing vectors and drug resistance marker genes different from those of the existing vectors is produced. The present invention provides an animal cell expression vector containing a multicloning site and a puromycin resistance gene or a blasticidin S resistance gene as a drug resistance marker gene, the expression of which is controlled by SV40 ori and SV40 pA.