A vehicle occupant detection apparatus includes an image pickup device for imaging an area including a position of a vehicle occupant within a vehicle compartment, a light emitting element for emitting auxiliary light into the compartment that includes the imaging area of the pickup device, and a storage section for storing imaging information provided by the pickup device. The vehicle occupant detection apparatus further including a comparison section for comparing imaging information provided through further imaging by the pickup device and the imaging information stored in the storage section, to provide a difference between the imaging information provided through the further imaging and the stored imaging information, and an abnormality determination section for determining abnormality of the imaging information on the basis of the image information difference.