In preventive maintenance to carry out check and maintenance before outbreak of a trouble, needs of condition based maintenance (CBM) increases. CBM is a method to carry out check and maintenance when it always observe an apparatus and grasp a sign of the deterioration. This report the result that examined a switch by an electromagnetic actuator. A characteristic of this method is to be able to grasp deterioration from change of the current and voltage of the electromagnet coil. Therefore, to watch a state without adding a sensor. As a result, confirmed that a change the operation waveform of the electromagnetic actuator on the condition that simulated a change of state. Therefore, state monitoring of the switch is enabled by operation waveform change.
