A golf ball including a spherical core and a cover. The cover has a nominal thickness of 0.1 mm to 1.2 mm. A dimple is formed on the surface of the cover. A concave portion is formed on the surface of the core. The position of the concave portion corresponds to that of the dimple. 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.