A control device which is configured to control a laser irradiation device to record visible information on a medium by irradiation of a laser beam, the control device comprising: a drawing information storage unit configured to store drawing information of line segments contained in line images of characters, numbers, and symbols; a drawing information acquiring unit configured to acquire, from the drawing information storage unit, drawing information of a line image as an object to be drawn; a thickness information acquiring unit configured to acquire thickness information which specifies a thickness of each line segment; an overlapping line segment detecting unit configured to detect a pair of line segments drawing ranges of which, inclusive of the line segment thickness, overlap each other, based on the thickness information and the drawing information; and a line dividing/shortening unit configured to divide or shorten at least one of the pair of line segments so that the drawing ranges of the pair of line segments do not overlap each other, characterized in that: the overlapping line segment detecting unit comprises: an intersection detecting unit configured to detect an intersection of a pair of line segments; an altitude computing unit configured to compute an altitude from an endpoint of one line segment of the pair of line segments perpendicular to the other line segment of the pair of line segments; an altitude intersection determining unit configured to determine whether the altitude intersects the other line segment of the pair of line segments; and a distance detecting unit (115, 116) configured to detect, when the pair of line segments have an intersection, a distance between the intersection and the pair of line segments as being zero, detect a distance between an endpoint of one line segment of the pair of endpoints and an endpoint of the other line segment, and detect, when the altitude intersects the other line segment, a length of the altitude from the endpoint of one line segment of the pair of line segments to the other line segment. a drawing information storage unit configured to store drawing information of line segments contained in line images of characters, numbers, and symbols; a drawing information acquiring unit configured to acquire, from the drawing information storage unit, drawing information of a line image as an object to be drawn; a thickness information acquiring unit configured to acquire thickness information which specifies a thickness of each line segment; an overlapping line segment detecting unit configured to detect a pair of line segments drawing ranges of which, inclusive of the line segment thickness, overlap each other, based on the thickness information and the drawing information; and a line dividing/shortening unit configured to divide or shorten at least one of the pair of line segments so that the drawing ranges of the pair of line segments do not overlap each other, the overlapping line segment detecting unit comprises: an intersection detecting unit configured to detect an intersection of a pair of line segments; an altitude computing unit configured to compute an altitude from an endpoint of one line segment of the pair of line segments perpendicular to the other line segment of the pair of line segments; an altitude intersection determining unit configured to determine whether the altitude intersects the other line segment of the pair of line segments; and a distance detecting unit (115, 116) configured to detect, when the pair of line segments have an intersection, a distance between the intersection and the pair of line segments as being zero, detect a distance between an endpoint of one line segment of the pair of endpoints and an endpoint of the other line segment, and detect, when the altitude intersects the other line segment, a length of the altitude from the endpoint of one line segment of the pair of line segments to the other line segment. an intersection detecting unit configured to detect an intersection of a pair of line segments; an altitude computing unit configured to compute an altitude from an endpoint of one line segment of the pair of line segments perpendicular to the other line segment of the pair of line segments; an altitude intersection determining unit configured to determine whether the altitude intersects the other line segment of the pair of line segments; and a distance detecting unit (115, 116) configured to detect, when the pair of line segments have an intersection, a distance between the intersection and the pair of line segments as being zero, detect a distance between an endpoint of one line segment of the pair of endpoints and an endpoint of the other line segment, and detect, when the altitude intersects the other line segment, a length of the altitude from the endpoint of one line segment of the pair of line segments to the other line segment.