The manufacturing method of permalloy soft magnet with the Ni contents of 46.6 and 47.2 wt% was investigated by powder injection molding technology. The magnetic properties of permalloy were greatly affected on the residual carbon and oxygen content of the sintered magnet. Solvent extraction and thermal debinding process to minimize the residual carbon content in sintered magnet were developed by controlling the debinding atmosphere. The residual carbon content depends on the debinding condition of the binder system for powder injection molding and the residual oxygen content on the sintering atmosphere. The sintered magnet produced by powder injection molding process had a 50 ppm. residual carbon, 150 ppm. residual oxygen. The coercivity and maximum relative permeability of permalloy soft magnet were 0.46 Oe and 14,600 respectively.