A method of manufacturing a package module structure of a high power device using a metal substrate that can improve reliability by minimizing stress due to a thermal expansion coefficient difference between a metal substrate and a semiconductor device includes: preparing a metal substrate; forming an oxide layer by selectively anodizing the metal substrate; forming a mounting groove for mounting a semiconductor device by etching a portion of the oxide layer; installing a shock-absorbing substrate that is made of a material having a thermal expansion coefficient in a range similar to a material of a semiconductor device to expose the entirety or a portion of a bottom portion of the mounting groove; mounting the semiconductor device in the shock-absorbing substrate exposed to the mounting groove; and electrically connecting an electrode terminal of the semiconductor device and an electrode line formed in an upper surface of the oxide layer.