The present invention relates to a SAMiRNA-magnetic nanoparticle complex capable of efficiently delivering double-stranded RNA oligonucleotides and magnetic nanoparticle to cells and to a composition comprising the SAMiRNA-magnetic nanoparticle complex, capable of both diagnosing and treating diseases such as cancer. More particularly, the present invention relates to a SAMiRNA-magnetic nanoparticle complex wherein a double-stranded RNA oligonucleotide-polymer structure in which double-stranded RNA oligonucleotides and a hydrophilic material and a second hydrophobic material are connected by a simple covalent bond or a linker mediated covalent bond and a magnetic nanoparticle in which a first hydrophobic material is bonded to the surface of a magnetic material are formed into a core. The first hydrophobic material of the present invention performs a hydrophobic interaction with the second hydrophobic material of the double-stranded RNA oligonucleotide structure so as to form SAMiRNA-magnetic nanoparticle complexes having a uniform size. In addition, the hydrophilic material and the second hydrophobic material bonded in the double-stranded RNA oligonucleotide structure may improve in vivo stability of the double-stranded RNA oligonucleotides. A ligand which is additionally bonded to the structure may deliver a SAMiRNA-magnetic nanoparticle complex to a target cell even when a small amount of the ligand is applied, and a magnetic material of the magnetic nanoparticle may be used as an imaging agent for diagnosis.
