  We have made a new survey of emission-line stars in the W5E HII region to
investigate the population of PMS stars near the OB stars by using the Wide
Field Grism Spectrograph 2 (WFGS2). A total of 139 H-alpha emission stars were
detected and their g'i'-photometry was performed. The spatial distribution of
them shows three aggregates, i.e., two aggregates near the bright-rimmed clouds
at the edge of W5E HII region (BRC 13 and BRC 14) and one near the exciting O7V
star. The age and mass of each H-alpha star were estimated from the extinction
corrected color-magnitude diagram and theoretical evolutionary tracks. We
found, for the first time in this region, that the young stars near the
exciting star are systematically older (4 Myr) than those near the edge of the
HII region (1 Myr). This result supports that the formation of stars proceed
sequentially from the center of HII region to the eastern bright rim. We
further suggest a possibility that the birth of low mass stars near the
exciting star of HII region precede the production of massive OB stars in the
pre-existing molecular cloud.
