To quickly and precisely confirm desired status information by a simple operation.

In response to a confirmation instruction with respect to notified warning, neighboring status information in a predetermined period including a point of time when warning is given is read from a storage part 13, and display-outputted by a data display means 11A of a control part 11. In response to a display request with a management point and a target date designated, the status information collected from the management point on the target date is read from the storage part 13, and display-outputted as a graph by the data display means 11A. In response to a selection instruction to select a point of time when the status information displayed as the graph is precisely displayed, the neighboring status information in a period before and after the point of time is read from the storage part 13, and display-outputted by the data display means 11A.