Porous composite

A porous composite comprising:

• a porous base material;
• and
• a porous collection layer formed on said base material,
• wherein said base material has a honeycomb structure whose inside is partitioned by a partition wall into a plurality of cells extending in a longitudinal direction,
• said plurality of cells include a plurality of first cells whose one ends in the longitudinal direction are sealed, and a plurality of second cells whose other ends in the longitudinal direction are sealed, said plurality of first cells and said plurality of second cells being arranged alternately,
• said collection layer covers inner surfaces of said plurality of first cells,
• an overall Sa that is an arithmetical mean height Sa indicating a surface roughness of a surface of said collection layer in said plurality of first cells is greater than or equal to 0.1 μm and less than or equal to 12 μm, and
• an overall mean thickness that is a mean thickness of said collection layer in said plurality of first cells is greater than or equal to 10 μm and less than or equal to 40 μm.