At least one layer in a coating located on a surface of a substrate is a domain structure layer constituted of two or more domains different in composition and a thin layer located between the domains and being different in composition from each of the domains. The thin layer is located between any one domain and any another domain and in contact therewith. When the size of each of a plurality of first domains present in the domain structure layer is defined as a diameter of a virtual circumcircle in contact with each first domain, the average value of the size of each first domain is not smaller than 1 nm and not greater than 10 nm and a thickness of the thin layer in a direction of thickness of the domain structure layer is not less than 1 atomic layer and not more than 10 atomic layers.