We have developed Cu-Zn/Al2O3/Al-plate catalysts for the methanol steam-reforming reaction. They were prepared by supporting the catalyst metals (copper and zinc) on alumina layers of anodized aluminum surfaces with and without a pore widening treatment. Characterization and methanol steam-reforming tests showed that a BET surface area and roughness factor were considerably increased by the pore widening treatment. However, the treated catalyst supported less copper and zinc than the untreated one. Copper and zinc were highly dispersed to pores inside the treated catalyst, while they congregated and aggregated on the catalyst surfaces to form larger particles in the untreated one. The prepared plate catalysts had high catalytic activity for the methanol steam-reforming reaction, and they had much lower catalytic-activity deterioration rates than the commercial CuO-ZnO catalyst. The pore-widened plate showed a lower deterioration rate than the non-pore-widened one, in which only the supported amount of copper decreased after the steam-reforming test. Thus, the pore widening treatment can suppress catalyst deterioration.