NOVELTY - Magnetic particle-containing medicinal formulation comprises a hollow magnetic particle, magnetic cage-shaped structure (10) which comprises sintered material obtained from metallic nanoparticles, and a coating layer (40), where the material is projected on a two-dimensional plane, and processed in terms of transmission electron microscope image. The porosity of the sintered material is calculated by determining proportion of transparent portions to the whole area inside the sintered material.    USE - The magnetic particle-containing medicinal formulation is useful for delivering drug including DNA, peptide and protein, preferably anticancer agent, treating diseases by transferring cell and gene or by thermotherapy, diagnosing diseases using magnetic resonance imaging, magnetic sensor or NMR imaging, screening drugs, preferably influenza drug, isolating bacteria, cell, and nucleic acid, and separating and purifying nucleic acid, protein and immobilized enzyme, and used in magnetic toner, magnetic ink, magnetic coating material, catalyst carrier and fuel cell.    ADVANTAGE - The medicinal formulation improves drug efficacy, and reduces side effects. The magnetic nanoparticle has excellent biocompatibility and magnetic induction property.    DETAILED DESCRIPTION - Magnetic particle-containing medicinal formulation comprises hollow magnetic particle, magnetic cage-shaped structure (10) which comprises sintered material obtained from metallic nanoparticles including iron, cobalt, or nickel, where the material is projected on a two-dimensional plane, and processed in terms of transmission electron microscope image. The porosity of the sintered material is calculated by determining proportion of transparent portions to the whole area inside the sintered material, where the proportion is 1-50%, and a coating layer (40) which covers at least one portion of surface layer of the magnetic particle. The medicinal formulation comprises medical agent (30) within the magnetic cage-shaped structure and/or in the coating layer. An INDEPENDENT CLAIM is included for method for preparing the magnetic particle, which involves preparing pre-casting template particle containing inorganic materials in which surface of the particle is modified, preparing casting template particle having first polarity with the first surface and second polarity opposite to the first polarity, and adsorbing the particles on the second polarity, where the particle is allowed to grow on the spot.    DESCRIPTION OF DRAWING(S) - The drawing shows typical conceptual view of magnetic particle-containing medicinal formulation.    Magnetic cage-shaped structure (10)    Medical agent (30)    Coating layer (40)