In this study, dynamic penetration phenomena of high-velocity impact of magnesium alloy were investigated. The surface hardness of magnesium alloy (AZ31B-O) and the heat-treated magnesium alloy (AZ31B-200°C, AZ31B-300°C, and AZ31B-430°C) were examined using Micro Vickers, and the influence of the heat treatment temperature was observed. We analyzed the metal organization using a microscope. We also used a ballistic range (two-stage light gas gun), and the test specimens were set at 0°obliquity at room temperature. A high-speed camera allowed us to capture and analyzed the dynamic penetration phenomena of the test specimen.