To enable a line to be drawn correctly under a simple constitution.

First, a center body 3 with a recessed part 3a is molded, then a surface part 1 is molded over the entire surface of the center body 3 excepting the recessed part 3a and thus a body part 4 is formed. In this case, the center body 3 is placed in a mold corresponding to the final size of a ball for a ball game, then only the recessed part 3a the center body 3 is fixed and a resin is poured into a space formed between the inner wall face of the mold and the center body 3 to mold the surface part 1. Finally, an area surrounding lines 2 to be formed on the body part 4 is set in the supporting mold. The part supporting the body part 4 of the mold has a curved surface along the contour of the body part 4 to assume a shape showing a space only in the line 2 part. This space is filled with the resin to mold the lines 2.