A process for producing an antibody enzyme which involves an antibody structure analysis step of confirming the presence of a catalyst triplet residue structure wherein a serine residue, an aspartate residue and a histidine residue or a glutamate residue are located stereostructurally close to each other in the stereostructure of an antibldy anticipated based on its amino acid sequence. Since the above-described catalyst triplet residue structure is a structure specific to an antibody enzyme, an antibody enzyme can be efficiently screened by using the same. Examples of the antibody enzyme as described above include an antibody enzyme against Helicobacter pylori urease and an antibody enzyme against chemokine receptor CCR-5.