Patent ID: 7887919

Claim:
An amorphous-carbon-based hard multilayer film formed on a substrate, comprising: a base layer formed at a substrate side; a surface layer formed at a surface side; and a compositional gradient layer formed between the base layer and the surface layer, wherein the base layer comprises a nitride or a carbo-nitride of an element M expressed by the following formula (1), the surface layer comprises an amorphous carbon film comprising C of 50 atomic percent or more, and the compositional gradient layer is a layer in which the element M and nitrogen are decreased, and carbon is increased from the base layer to the amorphous carbon film: M 1-x-y C x N y (1) wherein M comprises at least one selected from the group consisting of W, Mo and Ta; x and y denote atomic ratios; x is 0.5 or less; y is 0.03 or more; 1-x-y is more than 0, and wherein when a crystal structure of the base layer is examined by X-ray diffraction, an intensity of a maximum peak of an α-W structure, α-Mo structure, or TaN structure is at least five times as large as an intensity of peaks of other crystal structures.