An eye open state determination device includes an eyelid opening degree detector that detects a degree of opening of an eyelid of the subject from an image of an eye of a subject acquired by an image acquirer, a red eye generator that illuminates the subject with light to generate a red eye image on the image of the eye, a red eye detector that detects presence or absence of generation of the red eye image, an operation controller that activates the red eye generator at a timing different from a timing at which the image acquirer acquires the image of the eye, and a determinator that determines an eye open state of the subject based on the degree of opening of the eyelid and the presence or absence of generation of the red eye image.
Eye open state determination device and eye open state determination method