PURPOSE: To improve the durability of a sheathed ceramic tool by forming a sheath layer of Tic, TiN, TicN, Al2O3 or AlON, or the combination thereof on the surface of a base material comprising Al2O3-ZrO2 ceramic sinterd body having the predetermined composition of ZrO2 and Al2O3, using a CVD method.

CONSTITUTION: A base material is formed with an Al2O3-ZrO2 ceramic sintered body containing 1 to 5wt% of ZrO2, and Al2O3 as a remnant. In addition, a sheath layer comprising one or the combination of Tic, TiN, TicN, Al2O3 and AlON is formed on the surface of the base material via a CVD method. Also, the thickness of the sheath layer is set at a value between 0.3μm and 15μm. In this case, Tic, TiN and TicN may be used to form an inner layer and AlON to form an intermediate layer, while Al2O3 being used to form an outer layer.