A precursor particle having a particle size of 10 nm or more and 1 μm or less, and comprising a first compound selected from an alkoxide, a hydroxide, a sulfate, a nitrate, a carbonate, or a carboxylate of magnetic metal containing at least one metal of Fe and Co, and a second compound selected from an alkoxide or a hydroxide, a sulfate, a nitrate, a carbonate, or a carboxylate of a metal element for forming an oxide, is prepared. Then the precursor particle is heated in a reducing atmosphere to form an insulating particle made of an oxide of the metal element by decomposing the second compound, and to precipitate a particle of the magnetic metal in the insulating particle at a particle size of 1 nm or more and 100 nm or less, thereby manufacturing a high frequency magnetic material.