PROBLEM TO BE SOLVED : To provide a heavy metal stabilization agent excellent in low temperature stability and a manufacturing method therefor, and a stabilization method of heavy metal using the same. SOLUTION : The heavy metal stabilization agent contain water and piperazine-N, N' -bisdithiocarbamate, and having specific gravity of 1.190 to 1.235. The manufacturing method of the heavy metal stabilization agent has a process for preparing a mixture containing water and piperazine-N, N' -bisdithiocarbamate, and a process for adjusting the specific gravity of the mixture to 1.190 to 1.235. The stabilization method of heavy metal has a process for mixing the heavy metal stabilization agent to a heavy metal-containing article. The stabilization method of heavy metal has a process for obtaining the heavy metal stabilization agent by the manufacturing method of the heavy metal stabilization agent and a process for mixing the heavy metal stabilization agent to the heavy metal-containing article. SELECTED DRAWING : Figure 1 COPYRIGHT : (C)2019, JPO&INPIT