Low-frequency Raman measurement was performed in alkali and alkaline-earth silicate glasses to elucidate the effect of introduction of network modifiers on boson peak nature. Our study illustrated that introduction of small/medium ions tended to increase in the boson peak frequency (½ BP ), whereas the introduction of large ions tended to decrease the frequency. Although ½ BP has been suggested to be proportional to the shear modulus, no linear relationship was obtained in these binary systems. Instead, we experimentally demonstrated that mean atomic volume can explain variations in ½ BP regardless of the trend of boson peaks.©2013 The Ceramic Society of Japan. All rights reserved.Key-words : Glass, Raman scattering, Silicate, Boson peak, Optical spectroscopy [Received September 25, 2013; Accepted October 31, 2013] Silicate minerals are widely deposited in the earth's crust, thereby making silicate glass easily available. Historically, silica and silicate-system glasses have been used in lenses, optical fibers, displays of mobile devices, etc. because of their good transparency and thermal/mechanical resistance, contributing greatly to the development of modern science and culture. Nowadays, silica/silicate glasses have been intensively investigated for applications in photonic technology.