To identify antigens of the 2D7 antibody, the present inventors cloned the 2D7 antigen. The results suggested that the 2D7 antigen is an HLA class I molecule. Based on this finding, the present inventors examined whether the 2D7 antibody has cell death-inducing activity. Nuclei fragmentation was observed when the 2D7 antibody was cross-linked with another antibody, indicating that cell-death was induced. Further, diabodies of the 2D7 antibody were found to have very strong cell death-inducing activities, even without the addition of another antibody. These results indicate that minibodies of an HLA-recognizing antibody can be used as cell death-inducing agents.