Microcapsules, of which the wall material was made of calcium silicate, with a core material of thermal-sensitive pigment were prepared by interfacial reaction in multiple dispersion. The microcapsules obtained were characterized as follows. The shape was observed with a low-vacuum scanning electron microscope (LVSEM). The size was directly measured from the LVSEM micrgraphs. The yield was evaluated by the total mass balance of the materials involved. The color was observed by the naked eye. Effects of the concentration of stabilizer and the impeller speeds on the mean particle size and the yield were investigated.