PURPOSE: To save the consumption of activated alumina by depositing and coating a polymeric film on the part of a catalyst carrier on which activated alumina is not to be deposited, then depositing activated alumina on the catalyst carrier, and subsequently drying and baking the material.

CONSTITUTION: The polymeric film 7 is coated on the parts 6 and 6, of the catalyst carrier 5 on which alumina is not to be deposited, the film is melted by the heat of the carrier 5 and bonded to the carrier, and the parts are masked. The monolithic carrier coated with the polymeric film 7 is dipped in an activated alumina slurry, then dried, and baked. Consequently, the polymeric film 7 is burned and decomposed, the alumina on the polymeric film 7 loses its base and is removed, and a monolithic carrier having the parts on which activated alumina is not deposited is obtained. Since the wettability on the polymeric film is low, the amt. of activated alumina deposited is reduced and the consumption of activated alumina can be saved.