Disclosed is a method for manufacturing a flux cored wire for welding stainless steel of 0.9-1.6 mm in diameter having a seamed portion, which the method includes the steps of: forming a hoop (stainless steel 304L or 316L) into a U-shape and filling the hoop with a flux mixture, thereby forming a tube having a seamed portion; performing a primary drawing process on the tube shaped wire using a lubricant; performing a bright annealing process to relieve work hardening of the primarily drawn wire; performing a secondary drawing process on the wire until an accumulated reduction ratio after the bright annealing process falls within the range of 38-60%; physically removing a lubricant residue on the surface of the secondarily drawn wire; and coating the wire with a surface treatment agent.