The honeycomb filter is constructed as a diesel particulate filter having a filtration function for filtering out the particulate matter included in an exhaust emission of a diesel engine. The honeycomb filter has a honeycomb structure as a base and inlet opening cells with surface layers formed on respective inner surfaces thereof. The surface layer has zero film thickness in an inlet peripheral region. Separation vortexes are generated in the inlet peripheral regions. The zero film thickness of the surface layers in the inlet peripheral regions naturally causes non-flaking of the surface layers induced by the separation vortexes generated in the inlet peripheral regions and thereby leads to non-production of flakes. In the non-existent condition of flakes, the overall surface layers are not collapsed by collision of the flakes.