A pneumatic tire having a low air permeability, an improved fatigue resistance and a low fuel consumption is disclosed, which comprises an inner liner made of a vulcanizate of a rubber composition comprising 3-30 parts by weight of micro organic short fibers and 10-100 parts by weight of carbon black on a basis of 100 parts by weight of a rubber blend consisting mainly of butyl rubber and/or halogenated butyl rubber; said micro organic short fiber consisting of an amorphous portion having a glass transition temperature of less than 30.degree. C. or more than 120.degree. C. and a crystal portion having a melting point of not less than 160.degree. C., and having an average length of 0.8-30 .mu.m, an average diameter of 0.02-0.8 .mu.m and a ratio of average length to average diameter of 8-400.