ABNORMALITY DETECTION DEVICE AND ABNORMALITY DETECTION PROGRAM

An abnormality detection device is provided to detect an abnormal posture of a driver of a vehicle based on information of an image captured by an imaging unit for which an imaging region is defined to image a head of the driver. The abnormality detection device is configured to define at least one premonition region in a range in which the head is supposed to be positioned in process of transitioning from a normal posture to the abnormal posture in the imaging region. When the head stays in a premonition region, the abnormality detection device determines that the driver is in a state of the abnormal posture.