The present invention has for its subject to avoid a situation that condensed water stays around electrode terminals, in an electric heating type exhaust gas purification apparatus which is arranged in an exhaust system of an internal combustion engine. In order to solve this subject, the present invention resides in an exhaust gas purification apparatus of an internal combustion engine which is provided with a catalyst carrier having electrodes, a case in which the catalyst carrier is accommodated, a mat member arranged between the catalyst carrier and the case, a space part extending from the catalyst carrier to the case while passing through the mat member, and electrode terminals accommodated in said space part for supplying electric power to the electrodes of the catalyst carrier, wherein exhaust gas and condensed water are kept from permeating into the space part through the mat member or the catalyst carrier, by the provision of a pressure supply unit which supplies a positive pressure to the space part.