Wide period can range adjust the degree of corrosion resistance, to maintain sufficient strength for a desired period of time, then provides a magnesium-based medical device and a manufacturing method thereof capable of loss at a desired period. Magnesium-based medical devices of the present invention, there is provided a magnesium based medical device substrate is made of magnesium or its alloy, corrosion-resistant coating is formed on the substrate surface, the surface in the plane direction of the surface of the corrosion barrier coating is formed variation in hardness, characterized in that it is a 21 lower than the distributed value of Vickers hardness.