A method for metal powder injection molding includes injecting a first metal powder of a TiAl-based intermetallic compound into a mold, and molding the first metal powder through use of an injection molding machine; injecting a second metal powder of a TiAl-based intermetallic compound having a same constituent as the first metal powder and having a different average particle diameter from the first metal powder into a mold, and molding the second metal powder through use of the injection molding machine; and sintering molded articles obtained by molding the first metal powder and the second metal powder, and producing a mixed sintered compact in which a first sintered compact of the molded article obtained by molding the first metal powder and a second sintered compact of the molded article obtained by molding the second metal powder are integrated.