Abstract: The present invention relates to an oncolytic adenovirus capable of co-expressing interleukin-12 and a C-met-inhibiting oligonucleotide; and an antitumor immune-boosting composition and anticancer composition comprising the oncolytic adenovirus. The present invention has first identified an adenovirus system having simultaneous effects of IL-12 expression and C-met inhibition in cancer gene treatment. The adenovirus system of the present invention is capable of inhibiting C-met while expressing interleukin-12, thereby restoring immune functions in a tumor environment to enhance anticancer effects such as the inhibition of tumor recurrence and tumor growth and to inhibit tumor migration. Accordingly, the adenovirus system of the present invention can be effectively used in the treatment of cancer.