The invention provides a solid golf ball having a core and a cover. The core is formed of a rubber composition containing a base rubber, a co-crosslinking agent, a crosslinking initiator and a metal oxide. The co-crosslinking agent is methacrylic acid, and the rubber composition includes a specific waste material in the form of a powder. The core deflection and the cover material are optimized. Utilizing a waste material in a solid golf ball conserves resources and thus is beneficial to the global environment. Even during prolonged use, the golf ball maintains its basic performance attributes (feel, flight, durability) at a high level.