Converting rough sketches into line drawings is a mechanical and simple process in illustration production. Therefore, it is desirable to automate the process. Previous methods for automatically generating line drawings from rough sketches produce only uniform line drawings although rough sketches contain information about the strength of lines. In this paper, we propose a method that automatically converts rough sketches into non-uniform line drawings by estimating the thickness and the directions from the rough sketch and adding this information to the uniform line drawing. We evaluate the proposed method, and the generated non-uniform line drawings reflect the thickness and the direction of the rough sketch. While adding thickness manually takes about 20 to 30 minutes, the proposed method can generate a non-uniform line drawing in 1 to 2 seconds. It is a significant reduction in processing time.