The purpose of this study is to propose available activities at the sites of early childhood education by analyzing effect that phonological awareness activities using letter books have on children’s phonological awareness ability. The test treatments were conducted throughout a total of 16 times for six weeks from Sep. to Oct. in 2014. Young children of the test group conducted phoneme awareness activities after reading letter books. Young children of the comparison group conducted only reading of letter books. Young children of the control group implemented activities according to living subjects. After the test treatments, to find out the effect that phonological activities using letter books have on the phoneme awareness ability, the post-test was conducted. From conducting one-way ANOVA about syllable dropping, syllable distinction, phoneme counting, phoneme dropping, phoneme synthesis, and phoneme distinction as subordinate areas of phoneme awareness, differences among groups were analyzed. When the results of this study are summarized, they are like the next. First, it was shown that to conduct phonological activities using letter books positively influenced the phonological awareness ability of young children more than to conduct only reading letter books or to do activities related with living subjects without reading letter books. It was represented that to only read letter books had more positive effect on the phonological awareness ability than to do activities related with living subjects without reading letter books.