MgO based cement for the low-temperature calcination of magnesite required less energy and emitted less CO2 than the manufacturing of Portland cements. Furthermore, adding reactive MgO to Portland-pozzolan cement can improve their performance and also increase their capacity to absorb atmospheric CO2. In this study, the basic research for magnesia cement using MgCO3 and magnesium silicate ore (serpentine) as starting materials was carried out. In order to increase the hydration activity, MgCO3 and serpentinite were fired at a temperature higher than 600oC. In the case of MgCO3 as starting material, hydration activity was highest at 700oC firing temperature; this MgCO3 was completely transformed to MgO after firing. After the hydration reaction with water, MgO was totally transformed to Mg(OH)2 as hydration product. In the case of using only MgCO3, compressive strength was 35 kgf/cm2 after 28 days. The addition of silica fume and Mg(OH)2 led to an enhancements of the compressive strength to 55 kgf/cm2 and 50 kgf/cm2, respectively. Serpentine led to an up to 20% increase in the compressive strength; however, addition of this material beyond 20% led to a decrease of the compressive strength. When we added MgCl2, the compressive strength tends to increase.