Exhaust gas purification filter

An exhaust gas purification filter configured to be disposed in an exhaust passage of a gasoline engine, comprising:

• a cell assembly having an outer surface and including:
• a plurality of cells each disposed to extend in an axial direction of the filter, each of the cells having a quadrangular cross-sectional shape in a plane orthogonal to the axial direction, and each of the cells having opposing first and second ends in the axial direction, and
• a partition wall configured to have a porous structure and define the plurality of cells partitioned from each other;
• a plurality of seal members disposed alternately in the first and second ends of the respective cells, each of the seal members being configured to seal a corresponding one of the first end and the second end of a corresponding one of the cells of the cell assembly;
• and
• a skin member configured to have a tubular shape and be mounted on the outer surface of the cell assembly, wherein
• the partition wall has a porosity P1 of 50% to 70%, and the skin member has a porosity P2 of 50% to 70%,
• the porosity P1 of the partition wall and the porosity P2 of the skin member satisfy a relationship P1<P2,
• a porosity difference ΔP between the porosity P2 of the skin member and the porosity P1 of the partition wall is 20% or less, and
• the partition wall includes a plurality of crossing portions,
• each of the cells has at least one part of an outer periphery defined by a corresponding one of the crossing portions,
• the at least one part of the outer periphery of each of the cells is rounded to have a radius of curvature R,
• each of the cells has a radius r of a hydraulic diameter,
• the radius of curvature R and the radius r of the hydraulic diameter satisfy a relationship 0.2<R [mm]/r [mm]<1.