The present invention relates to a double-stranded oligo RNA structure comprising double-stranded miRNA, and a composition for preventing or treating cancer, containing the same. More specifically, the present invention relates to an anti-cancer pharmaceutical composition, containing: a double-stranded oligo RNA structure comprising miR-3670, miR-4477a and miR-8078, and characterized by a method for effectively inhibiting cancer cell proliferation or inducing cancer cell apoptosis； and a pharmaceutically acceptable carrier.
