PURPOSE: To provide a testing device which is usable for any machine parts, wear resistant, and capable of being easily improved into a practical one.

CONSTITUTION: A testing device to inspect a machine parts, in particular, a tool of a machine tool at the prescribed position is provided including a testing element 30 movable from the initial position by a moving means on a passage related to the position of the machine parts to execute the testing operation and a detector circuit 58 to transmit the test signal. The testing element includes a non-contact sensor 34, and the detector circuit 58 records the output signal A of the sensor during the testing operation, and transmits the test signal based thereon.