1. An interactive line-type recognizing method for recognizing interactively a line type of a line which has been specified to a pattern displayed by displaying a binary image data on a screen, comprising: memorizing in advance a line type pattern data in which a reference feature is registered for each constituent element which constitutes a line type pattern of the each line type; performing a labeling process based on the binary image data obtained from a drawing to generate a contour line data by taking out a contour line for each pattern according to the binary image data which is attained from the labeling process; identifying, when a line type of an objective line to be recognized on the screen and a position of a constituent element of the objective line has been specified, a type of the constituent element of the objective line according to the contour line data; and extracting a feature for the constituent element of the objective line, and then deciding whether or not the objective line is the same as the specified line type by comparing the extracted feature with the reference feature corresponding to the objective line, wherein at least four features, including a line segment, a node, a crosspoint, and an isolated point, are used as the constitute element.