1. A method of preparing a proliferation-regulated recombinant adenoviral vector, comprising the steps of: preparing a proliferation-regulated plasmid by (a) preparing an expression cassette in a plasmid that includes, in order from upstream to downstream, an E1A region, at least one protein-coding region in a E1B region or the entire E1B region, a poly(A) signal sequence, and a recombinase-recognizing sequence, by replacing an endogenous promoter in the E1A region and an endogenous promoter regulating expression of a protein-coding gene in the at least one protein-coding region in the E1B region with a first and a second multiple cloning site, respectively, and (b) introducing a first and a second promoter, each of which expresses specifically in a target organ, into the first and second multiple cloning sites, respectively; and integrating the proliferation-regulated plasmid into a plasmid containing an E1 region-deleted adenoviral genome.