A supporting device of a rotor includes a ceramic axial tube fixed on the rotor, and a ceramic axial support rotationally supporting the ceramic axial tube, wherein the spacing between the ceramic axial tube and the ceramic axial support is within the range of 2 25 .mu.m so as to prevent shaking and reduce noise. The ceramic axial tube formed as a hollow tube is allowed to store lubricants within the inner space of the tube, and further reduce frictional noise and heat production. In addition, the ceramic axial rube formed as a hollow tube is also advantageous for binding with the fan body during the molding process of the fan rotor.