This study was carried out to research on the optimum condition of $MgAl_2O_4$ spinel synthesis and the chara-ceteristics of its sintered bodies. In this study the used materials-MgO $Al_2O_3$-were prepared from the extragrade chemicals $Mg(OH)_2 Al(OH)_3$ respectively. The tendency to spinel synthesis and sintering condition were discussed about additives of SEM and the characteristics of sintered bodies were measured by TMA etc, The results were as follows ; 1. The addion of $TiO_2$ promoted more effectively the sinterbility than that of $MnO_2$. 2. Residual $alpha$-$Al_2O_3$ and MgO in theorectical composition samples were disappeared at 1$600^{circ}C$ 3. When added MnO2 residual $alpha$-$Al_2O_3$ and MgO were disappeared at 150$0^{circ}C$ and 1$600^{circ}C$ respectively. 4, . When added $TiO_2$ residual $alpha$-$Al_2O_3$ and MgO were disappeared at 150$0^{circ}C$ and 134$0^{circ}C$ respectively.