A golf ball which comprises a spherical core and a cover, wherein the cover has a nominal thickness of 0.1 mm to 1.2 mm. Dimples are formed on the surface of the cover and concave portions are formed on the surface of the core, the position of the concave portions corresponding to that of the dimples. The golf ball is obtained by forming the core by means of a mold having a large number of projections provided on a cavity surface thereof. By the projections, the concave portion is formed. When the cover is to be formed, the position of the core is determined in such a manner that the projections for forming the dimple correspond to the concave portions.