Tactile graphics are images that use raised surfaces so that a visually impaired person can feel them. Tactile graphics are necessary for visually impaired students when they study mathematics and science. Since producing tactile graphics is not simple task, an intelligent computer-aided system for assisting the production of tactile graphics is needed. Mathematical graph recognition from printed materials plays an important role in developing such a system. So, this paper focuses on part of a method of mathematical graph recognition. A mathematical graph consists of character strings, mathematical formulas and graph elements such as the rays representing the x-axis and the y-axis, and the straight lines or the curves representing functions or equations. Graph elements are drawn not only by solid lines, but also broken lines. This paper discusses a method for extracting and recognizing graph elements from mathematical graphs. The effectiveness of our method is evaluated by computer experiments.