We have studied the glass transition dynamics of trans-1,4-chloroprene from microscopic view points using a quasielastic neutron scattering technique in a time range of ∼4×10−13 to ∼4×10−10 s. It was found that the so-called fast process of picosecond order appears at around the Vogel–Fulcher temperature T0, similarly to cis-1,4-polybutadiene having no large side groups [J. Chem. Phys. 98, 8262 (1993)]. It is considered that the onset temperature at around T0 must be characteristic to polymers having no large side groups or no large internal degrees of freedom. In addition to the fast process, the slow process of subnanosecond order sets in at around the glass transition temperature Tg and the activation energy of the relaxation time was found to be ∼2.5 kcal/mol. The nature of the slow process is discussed in terms of conformational transition near Tg.