To provide a method of manufacturing a soft tennis ball with an integral inflation valve.

According to this manufacturing method, the soft tennis ball is formed by bonding two rubber semicircular bodies, the inflation valve is integrally provided by molding in an inner predetermined position of one semicircular body, a through hole is formed in the center of the inflation valve to insert an inflation tube of an inflator, and simultaneously an O-ring is fitted to the outside of the inflation valve in the interior of the semicircular body to prevent deformation of the inflation valve. Two semicircular bodies are respectively put in connecting molds, a pressure sensitive adhesive is applied to the contact surfaces of both semicircular bodies, and a suitable quantity of foaming agent is put in the two semicircular bodies. When the molds are closed and heated, the two semicircular bodies are bonded by an adhesive, and simultaneously the inner foaming agent is subjected to heat, so that it is inflated to touch the semicircular bodies and the inner walls of the bonding molds, whereby the spherical body can be supported in a round.