The universe contains much hydrogen from which Lyman αphotons radiate. Recently, many objects with a strong Lyman αline (LAE) were discovered at a very high redshift. Although the spatial distribution of LAEs is very important, it has not been described theoretically. Therefore, I am attempting to build up a picture of LAEs that is concordant with CDM cosmology. Moreover, to comprehensively understand galaxy evolution, I’m exploring how LAEs are related to galaxies observed with other methods.