We have carried out the thermal poling for 2Ag2O·3Na2O·25ZnO·70TeO2 (in mol%) glass sandwiched by two commercially available cover glasses and unexpectedly found that the Ag fine particles are selectively precipitated in the vicinity of the anode-side glass surface. The presence of Ag nanoparticles is confirmed by both X-ray diffraction and optical absorption measurements. Energy dispersive X-ray spectroscopy reveals that the glass composition near the anode-side surface becomes rich in Na+ after the thermal poling, which is caused by the migration of Na+ from the cover glass placed in between the glass sample and the anode. We consider that the glass network is softened by an increase in Na+ concentration to facilitate the Ag precipitation. Additionally we have developed a new method for forming micron-scale patterns of Ag nanoparticles on glass surface using a patterned cover glass fabricated by photolithography as an anode-side cover glass. © 2007 Optical Society of America.