Abstract: In a thread-wound golf ball comprising a two-layer structure center ball consisting of an inner layer and an outer layer, a rubber thread layer, and a cover, the center ball has a diameter of 30-36 mm and a weight of 19.5-31.5 g. The center ball outer layer has a specific gravity of 1.0-1.2, a Shore D hardness at least 5 units lower than the inner layer, and a thickness of 1-6 mm. The cover has a thickness of 1-3 mm. This construction and combination of characteristics gives the golf ball excellent spin, control, flight performance, and distance at all club head speeds, and especially increased distance when hit by a low head-speed golfer.