An eyelid opening level determination device includes a face image taking unit; an upper eyelid detection unit for detecting an upper eyelid in the face image; a lower eyelid area setting unit for setting an area for searching a lower eyelid based on the upper eyelid; an edge group detecting unit 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 unit for obtaining a reliability value of the edge group; a lower eyelid determination unit 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 unit for obtaining opening level of the eyelid based on positions for the upper eyelid and the lower eyelid.