Adhesion of a catalyst layer and an oxide film in a honeycomb substrate for catalyst support is improved. A honeycomb substrate for catalyst support used in purification of exhaust gas includes a honeycomb body and an oxide film that is formed on the surface of the honeycomb body and that has -alumina as a main component. The oxide film includes multiple oxide projections that are formed to be dispersed on the film surface and that include a contracted shape in which the width becomes narrower near the honeycomb body, and the density of the projection formations on the film surface is 0.20 (pieces/m.sup.2)-3.00 (pieces/m.sup.2).

Adhesion of a catalyst layer and an oxide film in a honeycomb substrate for catalyst support is improved. A honeycomb substrate for catalyst support used in purification of exhaust gas includes a honeycomb body and an oxide film that is formed on the surface of the honeycomb body and that has -alumina as a main component. The oxide film includes multiple oxide projections that are formed to be dispersed on the film surface and that include a contracted shape in which the width becomes narrower near the honeycomb body, and the density of the projection formations on the film surface is 0.20 (pieces/m.sup.2)-3.00 (pieces/m.sup.2).