PROBLEM TO BE SOLVED: To provide a magnesium-based material provided with a film having a corrosion resistance improving effect, its production method and a surface treatment method capable of coping with large members at low costs.SOLUTION: A magnesium-based material consists of a substrate composed of magnesium or a magnesium alloy and a film formed on the surface of the substrate. The film is composed of magnesium hydroxide (Mg(OH)) and an Mg-Al type laminar double hydroxide. For diffraction peaks in an X-ray diffraction of the surface of the film, the ratio (Y/X) of the peak intensity (Y) of the (003) plane of the Mg-Al type laminar double hydroxide to the peak intensity (X) of the (101) plane of the magnesium hydroxide is 0.05-0.3.
