PURPOSE: To form a catalyst layer with same thickness as a plane part by depositing a fine powder catalyst of perovskite having the specified structural formula on a monolithic catalytic carrier having a cell-like shape of quadrangle or hexagon by means of the specified deposition aid.

CONSTITUTION: Monolithic catalytic carrier 3, 4 of a cell-like shape of quadrangle or hexagon having corner parts 1, 2 of a curved shape are molded by using a heat resistant ceramic material such as cordierite or mullite. A catalytic layer 5 of perovskite composite oxide having a structural formula of La0.9Ce0.1 CoO3 is formed on the surface of these catalytic carriers. After immersing the catalytic carriers 3, 4 into kneaded slurry of particles of perovskite composite oxide and alumina sol, compressed air is blown to cell holes 6, 7 and the carriers are dried and thereafter calcined at about 800°C for 10min and the catalytic layer 5 is tightly stuck on the catalytic carriers 3, 4.