Substrate with surface-collection-layer and catalyst-carrying substrate with surface-collection-layer

A substrate with a surface-collection-layer that is used for a gasoline direct injection engine, the substrate comprising a honeycomb substrate that includes a porous partition wall that defines and forms a plurality of cells serving as exhaust gas passages, and has a number of pores, and a plurality of plugging sections that plug an inlet-side open end of given cells among the plurality of cells, and plug an outlet-side open end of the remaining cells, a surface-collection-layer that has an average pore size smaller than that of the partition wall being formed on a surface of the partition wall that defines the remaining cells, wherein the thickness of the surface-collection-layer on the outlet-side open end being larger than the thickness of the surface-collection-layer in a center area of the substrate in a cross section parallel to a center axis of the substrate, the partition wall having a thickness of 50.8 to 304.8 μm, a porosity of 50% or more and less than 70%, and an average pore size of 15 to 40 μm, the surface-collection-layer having a thickness of 10 μm or more and less than 100 μm, a porosity of 50% or more and less than 90%, and an average pore size of 0.1 μm or more and less than 10 μm, and the substrate having a cell density of 15.5 to 62.0 cells/cm2.