The porous silica glass prepared by the sol-gel method from the mixed solution of Si(OCH3)4, H2O, HCl and CH3OH with HCONH2 as a DCCA (Drying Control Chemical Additives). For investigation the characteristics of gels and glasses, we examined gels and glasses using TG-DTA, XRD, IR, SEM and porosimeter. The more content of formamide in the mixed solution increased, the more pore size and porosity of gel increased. In the excess formamide added gel, the properties of pore of gel were not so changed. The porous silica glass was prepared from the dry gel after heat treatment at 75$0^{circ}C$. Porosity and mean pore size of the porous silica glass was 17~25% and 40~60$AA$ relatively.