To inhibit seizure of the magnesium alloy on the surface of a component for the injection molding of a magnesium alloy from occurring and also to prevent any wear of the surface of the component from being caused.

Examples of films each of which is useful as a coating film 1 of a component 3 for the injection molding of a magnesium alloy, are: a film consisting of diamond-like carbon; a film consisting of a nitride, carbide or carbide-nitride of at least one metal selected from titanium, aluminum, chromium and their alloys; and further, a film that consists of ≥70% (atomic percent) of diamond-like carbon and also contains at least one metal selected from titanium, aluminum, chromium and their alloys.