Recent years, although silica aerogel is expected to be the material for energy savings, the lack of the strength prevents from commercial usages such as heat-insulating windows. To improve mechanical properties, methyltrimethoxysilane is used as a precursor of aerogels because the network becomes flexible due to the relatively low cross-linking density and to the unreacted methyl groups. Because of the strong hydrophobicity of MTMS-derived condensates, uniform and homogeneous gel networks are hardly attained. In this study, we employed surfactant n-hexadecyltrimethylammonium chloride (CTAC) in starting compositions to control phase separation during a 2-step acid/base sol-gel reaction. By changing the starting composition, properties of aerogels such as bulk density and light transmittance are affected. With increasing amount of CTAC, the gel networks became denser and less transparent. Highly transparent aerogels were obtained when the amount of urea was increased.