A thread-wound golf ball 1 producing excellent hit feeling, large carry and superior spin performance is provided having a rubber thread layer 3 formed by winding rubber thread around a center 2, which is further coated with a cover 4. It is provided that the opening adjacent to the stop has a convex section. The amplifier is coupled to the mixer and receives at least a portion of the bias current. The first dummy runner connects with the top runner and the top runner extends into a space between the mold cavities.