The invention provides a tubular molding material which is excellent in the bubble formation stability in producing a heat-shrinkable film. A tubular molding material consisting of a composition comprising a vinyl aromatic hydrocarbon/conjugated diene block copolymer, characterized in that the uniaxial elongational viscosity (Pa. sec) at 88 DEG C and a strain rate of 0.5sec<-1> satisfies the following relationship between 1.0 sec to 2.8sec after the initiation of elongation: 0.25<(LOG eta 2.8 - LOG eta 1.0)/(2.8-1.0)<0.4, wherein eta 1.0 and eta 2.8 are uniaxial elongational viscosities at elongation times of 1.0sec and 2.8sec respectively as determined with a Meissner-type elongational rheometer.