The present invention relates to a novel siRNA structure and the use thereof. More particularly, the invention relates to a double-stranded small interfering RNA molecule (siRNA molecule) comprising a 19-21 nucleotide (nt) antisense strand and a 15-19 nt sense strand having a sequence complementary to the antisense sequence, wherein the 5′ end of the antisense strand has a blunt end and the 3′ end of the antisense strand has an overhang, and to a method for silencing the expression of a target gene using the siRNA molecule.