Polytetrafluoroethylene（ PTFE） is extremely difficult to adhere to other materials due to its low surface energy and week boundary layer. Therefore, surface modification of PTFE is essential for expanding application range. Although heat-assisted plasma treatment was developed recently, stable treatment was impossible when the width of PTFE sheet was more than 300 mm because PTFE sheet waved and touched electrode due to thermal expansion of PTFE. In this study, we performed two types of heat-assisted plasma treatment in wide gap between electrode and PTFE surface in order to solve the problem and examined the influence of the gap on adhesion property of the plasma-treated PTFE. Heat-assisted plasma treatment by heating with increasing applied power for plasma generation successfully maintained high adhesion property when the gap between electrode and PTFE surface increased, so we solved the problem. On the other hand, adhesion strength decreased when the gap increased in heat-assisted plasma treatment by heating using a heater. In conclusion, we found that a heat-assisted plasma treatment by heating with increasing applied power is more useful for increasing adhesion property of PTFE than heat-assisted plasma treatment by heating using a heater when the gap increased.