Our group has developed a magnetically modified photocurable polymer for use in microstereolithography to fabricate magnetic microstructures and microactuators having three-dimensionally complex structures. This polymer is prepared by mixing a photocurable polymer with magnetic particles together with a viscosity-increasing agent for preserving the dispersion of the particles. In this study, we conducted experiments to evaluate the curing and magnetic characteristics of this magnetically modified photocurable polymer. We then rapidly fabricated truly three-dimensional magnetic microstructures by microstereolithography using this polymer. We expect that this achievement will lead to the development of magnetic microactuators.