Disclosed are a pneumatic tire, which exhibits excellent puncture-preventing function while avoiding inconvenience aroused when a sealant layer is formed based on decomposition reaction of polyisobutylene, a process for producing the same and a sealant rubber composition. This pneumatic tire is provided with the sealant layer in a region of the inner surface of the tire which corresponds at least to a tread. The sealant layer is made of an adhesive sealant obtained by heating a rubber composition containing 0.2 to 20 parts by weight of peroxide per 100 parts by weight of a rubber ingredient containing not less than 50 wt. % of polyisobutylene. 5 to 50 parts by weight of a liquid ethylene/ alpha -olefin copolymer, liquid polybutadiene or liquid polyisoprene are added as an adhesive of the sealant layer. <IMAGE>
