1. An alarm apparatus for sensing occurrence of abnormality in a plant that manufactures products by processing substrates, the alarm apparatus comprising: means responsive to an inspection result of a surface of the substrates during manufacturing the products for aggregating degree of occurrence of defects for each monitoring unit region to produce an aggregation result, the monitoring unit region having a prescribed size configured for each type of the abnormality; means for comparing the degree of occurrence of defects in each of the monitoring unit regions with a reference; and means responsive to detection of the monitoring unit region with the degree of occurrence of defects being higher than the reference for transmitting an alarm and outputting the aggregation result.