The honeycomb catalyst body is equipped with a honeycomb structure body having partition walls that define a plurality of cells extending from a first end face as one of the end faces to a second end face as the other end face and serving as through channels of a fluid. The partition walls each have a base layer containing from 50 to 90 mass % of zeolite and a coat layer with which the surface of the base layer 11 is coated with a thickness of from 1 to 50 μm. The coat layer is either a coat layer (A) containing from 1 to 5 mass % vanadia and titania or a coat layer (B) containing from 1 to 5 mass % vanadia and a composite oxide of titania and tungsten oxide.