The objective of this study is to investigate the emission mechanism of radiophotoluminescence(RPL)from Ag+-activated phosphate glass(glass dosemeter), which is now used as the individual radiation dosemeter, because the emission mechanism of RPL from glass dosemeter has not clearly been understood. The optical properties such as optical absorption spectra, RPL emission and excitation spectra of the Ag+-activated phosphate glass were analyzed. It was found that the optical absorption spectra of X-ray irradiated glass consisted of three dominant absorption bands peaked at about 255nm, 315nm and 370nm. It was also found that typical RPL spectrum of X-ray irradiated glass excited with 315 nm UV light has two emission bands peaked at about 460nm and 570nm. We also found that RPL intensity gradually increased after X-ray irradiation with elapsed time. It was also confirmed that 570nm RPL peak intensity increased with time, while the band around 460nm unchanged. This result strongly suggests that the 570nm RPL emission band is ascribed to Ag2+ ions. On the other hand, Ag+ activated phosphate glass irradiated with the femtosecond LASER-light exhibits photoluminescence emission peaked between 430 and 460nm, which strongly suggest that the 460nm RPL peak is ascribed to Ag0 ions because of valence change from Ag+ to Ag0.