To provide a method for forming an anodic oxide film which can be dyed in such a way that a metallic texture is exhibited while preventing or sufficiently reducing color irregularity and dullness and also to provide a method for coloring a magnesium material through the method.

A base material made of magnesium or magnesium alloy is immersed in an electrolytic solution containing alkali metal hydroxide and anodizing S3 is performed using the base material as one electrode without causing spark discharge to form the anodic oxide film. The magnesium material can be colored by performing a step S5 where the surface of the resultant anodic oxide film is dyed with dyes.