Molecular motions of polymer chains depend on blending; these motions are different in bulk and in a polymer blend. In this research, the molecular motions of poly(epichlorohydrin) (PECH) were studied by l3C NMR. They show different behavior in bulk from that in polymer blend. Two types of blend films, PECH/PMMA = 60/40 (wt%), were prepared from toluene and THF solution; the former is transparent and the latter is an opaque film. From the temperature dependence of line shape, T1, and T2 in PECH, it is found that the blend film shows the same behavior as bulk but at a higher temperature and that the opaque blend film shows behavior intermediate between that of bulk and that of the transparent film. This result shows that the molecular motion of PECH is inhibited by the surrounding PMMA chains and that the decrease in molecular motion depends on the phase structure. T2 is more sensitive to phase structure in polymer blend than T1. So the slow motion described by T2 is influenced by blending more than the fast one described by T1. © 1990, The Society of Polymer Science, Japan. All rights reserved.