Provided is metal insert-molded article (1) having excellent airtightness without necessity to perform a surface treatment for adhesion with a molding material. Metal material (3) having an aspect ratio of 1 to 10 in a cross section perpendicular to a lengthwise direction is insert-molded using molding material (2) having a crystalline thermoplastic resin as a main component and containing an inorganic filler in an amount of 0% by weight to 10% by weight.