PURPOSE: To simply and quickly perform trouble shooting at the time of failures by providing a display means for the result of condition diagnosis which can display the results of condition diagnoses on signals selected by a selection means in one screen to the extent of a specified number.

CONSTITUTION: Signals as a display object for the result of condition diagnosis are arbitrarily selected out of respective signals each result of condition diagnosis of which can be displayed by a condition diagnosis result display object signal selection means 12e. And next, a condition diagnosis result display means 12f allows the results of condition diagnoses for signals selected by the selection means 12e to be displayed in one screen to the extent of a specified number. By this constitution, the results of condition diagnoses for given signals can be displayed in one screen to the extent of a specified number. The results of condition diagnoses for respective signals can be compared with one another among arbitrary signals in a simple manner.