The electrical conduction of polyvinyl chloride was measured from low electric field to high field near breakdown below, in, and above a glass transition region. Ionic conduction was found to hold up to the field near breakdown. The estimated jump distance of a charge carrier changes considerably in the glass transition region, while it remains constant (12 Å) at a temperature fairly below the glass transitionTg(=87°C) and seems to reach a saturation value (30 Å) aboveTg. The elongation of substantial jump distance may be explained by the change in the shape and height of potential barriers against ionic migration due to the liberation of micro‐Brownian motion of main chains in the glass transition region.