Exhaust gas processing device

An exhaust gas processing device comprising:

• a pillar honeycomb structure including a honeycomb unit which is electrically conductive and which has cells which are separated by a cell wall and extend from a first end surface to a second end surface along a longitudinal direction of the honeycomb structure, the cell wall carrying a catalytic agent;
• a first inorganic mat member wound around an outer periphery of the honeycomb structure;
• a first cylindrical metallic member accommodating the honeycomb structure around which the first inorganic mat member is wound;
• a second inorganic mat member wound around an outer periphery of the first cylindrical metallic member;
• a second cylindrical metallic member accommodating the first cylindrical metallic member around which the second inorganic mat member is wound;
• and
• an insulating layer having a thickness of about 20 μm to about 400 μm and provided at least one of a first part between an inner surface of the first cylindrical metallic member and the first inorganic mat member, a second part between an outer surface of the first cylindrical metallic member and the second inorganic mat member, and a third part between an inner surface of the second cylindrical metallic member and the second inorganic mat member.