An eyelid opening level determination device (50) includes a face image taking means (10) an upper eyelid detection means (24) for detecting an upper eyelid in the face image a lower eyelid area setting means (24) for setting an area for searching a lower eyelid based on the upper eyelid an edge group detecting means (24) for detecting an edge group where brightness changes from dark to bright as a lower eyelid candidate by scanning the area from an upper side to a lower side a reliability value obtaining means (24) for obtaining a reliability value of the edge group a lower eyelid determination means (24) in which the edge group having the reliability value exceeding a predetermined value in the edge group is determined to be the lower eyelid and an eyelid opening level obtaining means (24) for obtaining opening level of the eyelid based on positions for the upper eyelid and the lower eyelid.
