Filter and method for manufacturing same

A filter comprising a plurality of pillar-shaped honeycomb structure segments made of porous ceramics, side faces of the segments being bonded together via a bonding material, wherein

• each of the pillar-shaped honeycomb structure segments comprises an outer peripheral side wall, and partition walls partitioning a plurality of cells extending from a first end face to a second end face, and
• in each of the pillar-shaped honeycomb structure segments, an average porosity of the outer peripheral side wall is lower than that of the partition walls, and the outer peripheral side wall is such that an average porosity of a region having a thickness of 20% or more of the outer peripheral side wall inward from an outermost peripheral portion of the outer peripheral side wall is 25% or less of that of the partition walls.