Aluminum oxide-coated article

An aluminum oxide-coated article having a first coating layer and a second coating layer formed in this order on a substrate, said first coating layer having a single- or a multi-layer structure and being made of at least one member selected from the group consisting of carbides, nitrides, carbonitrides, oxides, oxycarbides, oxynitrides and oxycarbonitrides of metals in Groups IVa, Va and VIa of the Periodic Table, and said second coating layer being constituted by at least one α-aluminum oxide-based oxide layer, which has an equivalent X-ray diffraction peak ratio PR (1 0 10) of 1.3 or more in a (1 0 10) plane, wherein a surface of said α-aluminum oxide-based oxide layer has an average crystal grain size of 1 μm or less when the oxide layer thickness is 2.5 μm or less, an average grain size of 2 μm or less when the oxide layer thickness is more than 2.5 μm and 4.5 μm or less, and an average grain size of 3 μm or less when the oxide layer thickness is more than 4.5 μm.