PURPOSE: To automatically, quickly and accurately inform only the proper information to a maintenance operator for the abnormal state of an electronic computer, by adding a deciding means for level of the abnormality.

CONSTITUTION: The abnormal state of a means 1 to be detected is detected by a detecting means 2 connected to the means 1 and the means 2 produces the abnormality information in response to said abnormal state. A transmission means 3 sends said information of the means 2 to a maintenance means 4. Receiving this information, the means 4 displays this information on a display means (not shown here) or a monitor operator of the means 4 to inform the occurrence of the abnormal state. Then it is checked whether the abnormality information received from the means 2 exceeds or not a workable range of the means 1. Thus the information is given to the means 4 only in case said abnormality information exceeds said workable range. Thus it is possible to omit delivery of information every time the abnormality occurs in the workable range of the means 1.