The present disclosure provides a waveguide filter including a casing configured to form a waveguide having a side wall, a part of which is formed with a through hole, a plurality of partitions configured to form resonance sections by partitioning an interior of the waveguide within the casing, a cap configured to have a body that is fitted within the through hole of the casing so as to define at least a part of an inner region of the waveguide, and to have a head formed to correspond to at least a part of a peripheral region around the through hole of the casing so that the head is coupled with the casing, and at least one tuning sheet configured to be held interposed between the head of the cap and the casing when coupled.