PURPOSE: To provide a monitor using a television camera.

CONSTITUTION: A monitored region Kj is provided in relation to the specified monitored object part of a monitored field of view FLD, and an action condition confirming region CON is provided in addition so as to take in luminosity data indicating the luminosity change of the monitored field of view FLD from the action condition confirming region CON. When the luminosity data exceeds the specified reference value, assessment action on the monitored region is inhibited, and the reference data is corrected into the value optimized for the luminosity change. Even the sudden luminosity change of the monitored field of view can be thereby met to prevent unnecessary abnormality judgment, so that the optimum assessment result can be obtained.