It is an object to provide a method for producing magnetic microparticles, which produces monodispersed magnetic microparticles, causes no clogging with a product due to self-dischargeability, requires no great pressure, and is excellent in productivity. In the method for producing magnetic microparticles, at least two fluids are used, and at least one kind of the fluids is a fluid containing at least one kind of magnetic raw material, and at least one kind of the fluids other than the above fluid is a fluid containing at least one kind of a magnetic microparticles-separating agent, and the respective fluids join together in a thin film fluid formed between two processing surfaces arranged to be opposite to each other so as to be able to approach to and separate from each other, at least one of which rotates relative to the other, whereby magnetic microparticles are separated in the thin film fluid to obtain the magnetic microparticles.