Calcium carbonate, especially aragonite which has needle-like morphology has been widely used as filler and coation agent in manufacturing industry of rubber, plastic, paper, etc. This study was conducted to investigate effects of $MgCl_2{cdot}6H_2O$ and $SrCO_3$ addition on synthesis of aragonite at $30^{circ}C$ to save energy in carbonation process. As a result, aragonite increased with the increase of $MgCl_2{cdot}6H_2O$ addition and in adding together $MgCl_2{cdot}6H_2O$ and $SrCO_3$ seed, amount of aragonite was increased with the increase of $SrCO_3$ seed at 0.2 mole of $MgCl_2{cdot}6H_2O$. This might be because the $Mg^{2+}$ ion prevented the change of calcite from aragonite which was formed by $SrCO_3$ seed.