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 defining a plurality of cells extending from an inflow side end surface to an outflow side end surface,
• wherein the plurality of cells include an inflow cell and an outflow cell adjacent across the partition wall,
• wherein the inflow cell has an open inflow side end and a sealed outflow side end,
• wherein the outflow cell has a sealed inflow side end and an open outflow side end,
• wherein the inflow cell side catalyst layer is disposed on an inflow cell side surface in an inflow cell side catalyst region extending from an inflow side end of the partition wall to a position apart by a distance of 10% or more of a length of the partition wall along an extending direction, and
• wherein, when a proportion of a filled portion filled with the inflow cell side catalyst layer in pores of the partition wall which are present in an inner region up to a depth of 50% of a thickness of the partition wall from the inflow cell side surface of the partition wall at a reference position apart from the inflow side end of the partition wall by a distance of 10% of the length of the partition wall along the extending direction is a proportion of an area of a filled portion filled with the inflow cell side catalyst layer in pores of the partition wall present in the inner region of the partition wall relative to an area of the pores of the partition wall present in the inner region of the partition wall in a cross-sectional surface perpendicular to the extending direction at the reference position of the partition wall, the proportion of the filled portion is 40% or less.