Exhaust gas purification device

An exhaust gas purification device comprising:

• a honeycomb substrate;
• and
• an inflow cell side catalyst layer,
• wherein the honeycomb substrate includes a porous partition wall, the porous partition wall defining a plurality of cells extending from an inflow side end surface to an outflow side end surface,
• wherein the plurality of cells include inflow cells and outflow cells adjacent to one another, the partition wall being interposed between the inflow cells and the outflow cells,
• wherein the inflow cells have open inflow side ends and sealed outflow side ends,
• wherein the outflow cells have sealed inflow side ends and open outflow side ends,
• wherein the inflow cell side catalyst layer is disposed on a surface on the inflow cell side in an inflow cell side catalyst region from an inflow side end to a position close to an outflow side end of the partition wall, and
• wherein a gas permeability of an outflow side partition wall portion including an outflow side region from the position close to the outflow side end to the outflow side end of the partition wall is higher than a gas permeability of a catalyst-disposed partition wall portion including the inflow cell side catalyst region of the partition wall and the inflow cell side catalyst layer.