The present invention relates to a metal-polymer resin composite in which a polymer resin is directly injection-molded to a zinc alloy, a magnesium alloy, or a die-casting part thereof, and thus an injection product is directly bonded to a metal surface, wherein in the case of a hard polymer resin, a tensile strength of the metal and the polymer resin is 30 MPa or greater, and in the case of a soft polymer resin, a tensile strength of the metal and the polymer resin is 20 MPa or greater, and an average helium leakage after 10 times of measurement is 10.sup.8 Pa.Math.m.sup.3/s or less, and a novel method for preparing the same.