Abstract: An uncrosslinked thermoplastic elastomer composition comprising:(A) 35-95% by weight of a 1,2-polybutadiene having a 1,2-configuration content of 70% or more, a crystallinity of 5-40% by weight and [.eta.] of 0.7 dl/g or more as measured at 30.degree. C. in toluene,(B) 1-20% by weight of an isobutylene polymer or an isobutylene-isoprene copolymer (preferably having a degree of unsaturation of 0-5 mole % and a viscosity average molecular weight of 7,000-80,000),(C) 5-40% by weight of a polybutadiene rubber having a 1,4-configuration content of 80% or more and(D) 0-30% by weight, preferably 5-30% by weight, of at least one member selected from the group consisting of isoprene rubber, natural rubber, acrylonitrile-butadiene rubber, styrene-butadiene rubber and ethylene-propylene type rubbers, wherein, preferably, (B)/{(C)+(D)}=2/1-1/20.