To develop porous glass membranes used for a effective membrane-separation process, porous glasses and glass membranes were prepared from the sodium borosilicate parent glass by the phaseseparation technique and effects of heat-treatment and leaching conditions on their characteristics were investigated. The crack-free glass membranes could be fabricated from the 9.4 Na2-O-30.7 B2O3-59.2 SiO2-0.7 Al2O3(wt%) parent glass by heat-treatment at the lower temperature(550-570$^{circ}C$) and for longer than 45 hrs for the phase separation, followed by leaching with 3N-HCl＋60% ethylene glycol solution at 90$^{circ}C$ over 25 hrs. Porous glasses prepared in this work showed large specific surface areas(400㎡/g) and narrow pore size distribution with the mean pore radius of 14${AA}$ enough for the application as reverse osmosis membranes. The salt-rejection efficiency and product-flux of the glass membranes heat-treated at 570$^{circ}C$ for 80 hrs were found to be 51.8% and 270cc/㎡. hr, respectively. This result suggests that the porous glass membranes fabricated in this study could be applied for the reverse osmosis process.