A sanding machine includes a number of machine elements, a number of sensors attached to the machine elements respectively, a malfunction indicating device having a graph disposed on a front panel for showing the machine elements, and a number of indicating members disposed on the front panel and coupled to the sensors for detecting malfunctions of the machine elements and for detecting whether the machine elements may not be operated or have become failed or have been damaged or not, and for allowing the malfunction areas to be easily and quickly found and repaired by the workers or the users.