Honeycomb filter

A honeycomb filter comprising:

• a honeycomb structure body having porous partition walls defining a plurality of cells which extend from an inflow end face as one end face to an outflow end face as the other end face and become through channels for fluid;
• inflow side plugging portions disposed in end portions of the predetermined cells on the side of the inflow end face;
• and
• outflow side plugging portions disposed in end portions of the residual cells on the side of the outflow end face,
• wherein the plurality of cells comprise outflow cells in which the inflow side plugging portions are disposed and inflow cells in which the outflow side plugging portions are disposed,
• in a cross section perpendicular to a cell extending direction, the whole periphery of each of the outflow cells is surrounded by an inflow cell group comprising the plurality of inflow cells which are adjacent to the outflow cell via the partition walls,
• the inflow cells constituting the inflow cell group are defined by inflow/outflow partition walls which are the partition walls defining the outflow cell and inflow/inflow partition walls which are the partition walls intersecting the inflow/outflow partition walls,
• a surface area A1 of the inflow/outflow partition wall of the inflow cell and a surface area A2 of the inflow/inflow partition wall of the inflow cell satisfy a relation of 1.2≤A1/A2≤2, and
• in the cross section perpendicular to the cell extending direction, when a region of each partition wall from its surface on the side of the inflow cell to a position of 10% of a length of the partition wall from the surface on the inflow cell side in a thickness direction of the partition wall is defined as a surface region R1 and a region of the partition wall from a position of 40% of the length of the partition wall from the surface on the inflow cell side in the thickness direction of the partition wall to a position of 60% of the length of the partition wall from the surface on the inflow cell side in the thickness direction of the partition wall is defined as a central region R2, an average pore diameter X of the surface region R1 is from 4 to 60% of an average pore diameter Y of the central region R2.