The present invention provides a polybutadiene having improved workability and abrasion resistance. A polybutadiene according to the present invention has: (A) a Mooney viscosity (ML.sub.1+4,100 C.) being 43 or more; (B) a ratio (Tcp/ML.sub.1+4,100 C.) of 5 wt % toluene solution viscosity (Tcp) to Mooney viscosity (ML.sub.1+4,100 C.) being 0.9 to 2.3; (C) a stress relaxation time (T80) being 10.0 to 40.0 seconds, which is a time until a torque is attenuated by 80% when the torque at the end of ML.sub.1+4,100 C.measurement is 100%; and (D) a molecular weight distribution (Mw/Mn) being 2.50 to 4.00.

The present invention provides a polybutadiene having improved workability and abrasion resistance. A polybutadiene according to the present invention has: (A) a Mooney viscosity (ML.sub.1+4,100 C.) being 43 or more; (B) a ratio (Tcp/ML.sub.1+4,100 C.) of 5 wt % toluene solution viscosity (Tcp) to Mooney viscosity (ML.sub.1+4,100 C.) being 0.9 to 2.3; (C) a stress relaxation time (T80) being 10.0 to 40.0 seconds, which is a time until a torque is attenuated by 80% when the torque at the end of ML.sub.1+4,100 C.measurement is 100%; and (D) a molecular weight distribution (Mw/Mn) being 2.50 to 4.00.