To stably and efficiently provide a clean substrate having excellent flatness without curling tendency and creak at the continuous heat treatment time of a polyester film obtained by continuously carrying the web-shaped polyester substrate, heat-treating the substrate at a temperature of glass transition temperature(Tg) or below and taking up the substrate in a roll state.

The continuous heat treatment method of the PET substrate is a method that the heat treatment of the web-shaped PET substrate 101 is executed at a temperature of the glass transition temperature or below while continuously carrying it. Then, vacuum glow discharge work for imparting adhesion and coating work for forming an electrical conductive layer in order to obtain an antistatic effect and an antiblocking effect are continuously executed in the order thereof for at least one surfaced of the substrate 101 during carrying. Besides, the heat treatment is executed in a state where the substrate 101 is taken up in the roll state.