A micro-machining method of manufacturing a micro fluxgate sensor manufactured having an amorphous magnetic core includes forming lower coils of an excitation coil and a magnetic field detecting coil on a wafer, depositing a first insulating layer on the lower coils and forming an amorphous magnetic core, depositing a second insulating layer on the amorphous magnetic core and forming upper coils connected to the lower coils to complete the excitation coil and the magnetic field detecting coil, and covering the excitation coil and the magnetic field detecting coil with a protective film, and etching the protective film to expose a portion of the excitation coil and magnetic field detecting coil, thereby forming a pad.