The production method of a radioactive metal-labeled antibody of the present invention includes a step of conducting a click reaction of a radioactive metal complex and an antibody site-specifically modified with a peptide to produce a radioactive metal-labeled antibody. The click reaction is performed between a first atomic group of the radioactive metal complex and a second atomic group directly or indirectly linked to the peptide. The second atomic group is an atomic group containing an azide group, or an atomic group containing trans-cyclooctene.