The invention provides a manufacturing device of an exciting magnet. The manufacturing device comprises a metal mould, a pair of magnetic field generating portions and a ferromagnetic component with a U-shaped plane section, wherein the metal mould is provided with a chamber with a rectangular plane section, the magnetic field generating portions are used for generating magnetic fields, and the ferromagnetic component is assembled in the chamber, so that magnetic lines generated by the magnetic field generating portions are concentrated to the U-shaped ferromagnetic component through magnet forming materials filled into the chamber.