An object of the present invention is to provide an HIV antibody-inducing peptide antigen that can be used without problems for HIV, which is highly prone to mutation, and is effective in developing an antibody or a vaccine having excellent specificity and binding activity even for the three-dimensional structure of a neutralization target, i.e. the mechanism by which HIV invades a target cell; a method for synthesizing the same; a vaccine comprising the peptide antigen, or an HIV three-dimensional structure-recognizing antibody induced by the peptide antigen; and a preventive and/or therapeutic agent for HIV infection comprising the peptide antigen, the vaccine, or the HIV three-dimensional structure-recognizing antibody as an active ingredient. The synthesis method comprises using a trimer of N36 peptide derivative which is synthesized by ligating a derivative of a helical region N36 peptide in N-terminal of an HIV particle transmembrane protein gp41 to a C3-symmetric template compound having three equivalent linker structures.