Provided is at least two of a direction determination unit which determines that the state is abnormal when a gaze direction of a driver of a vehicle is not within a first predetermined range based on a captured image of a head of the driver, a height determination unit which determines that the state is abnormal when a height of an eye of the driver is not within a second predetermined range based on the captured image, and a position determination unit which determines that the state is abnormal when a position of the head in a lateral direction is not within a third predetermined range based on the captured image; and an abnormal state determination unit which determines whether the state of the driver is abnormal based on the determination results of the determination units.