A position identifying unit (4) is configured to identify the location of a monitored person in the horizontal direction and maximum height of the monitored person in the vertical direction on the basis of top-down image data acquired by an upper image sensor (2) provided above a monitored area capturing an image of the monitored area and lateral image data acquired by a lateral image sensor (3) provided along a side of the monitored area capturing an image of the monitored area. An event determining unit (5) assesses a fall-related event for the monitored person on the basis of a location in the horizontal direction, a maximum height in the vertical direction.
