Abstract: The invention provides an antibody for human epidermal growth factor receptor 2 (Her2) concomitant diagnostic immunohistochemical detection (IHC). When the antibody is used as a primary antibody for immunohistochemical detection of Her2 expression, false positives in detection results caused by the absence of an extracellular region can be avoided. Moreover, the antibody can still recognize and bind to the corresponding epitope in the detection sample when the patient's immunohistochemical detection sample is not repaired by an antigen (or epitope), thereby reducing the issue of a false negative caused by the difference in repairing methods of the antigen (or epitope) in an IHC test.