Objectives: The main purpose of this study was to examine factors contributing the quality of life related to oral heath such as level of oral health knowledge, subjective knowledge on oral health, awareness of oral health and OHIP-14, and furthermore to analyze any relations among these factors. Methods: The questionnaire survey was carried out on a convenience sample of 230 middle school students at the selected middle school in Chungcheongnam-do. T-test and one-way ANOVA and correlation test were conducted over the collected datas using SPSS 12.0(SPSS 12.0 KOR for Windows, SPSS Inc, Chicago, USA). Results: The results of the study are as follows: 1. 6.38 was average score for oral health knowledge and 10.0 was the maximum. Subjective oral health awareness scored of average 2.99 with maximum of 5.0. OHIP-14 corresponded to average 4.30 and maximum 5.0. 2. Different level of oral heath knowledge was resulted from that of education, which means the greater level of oral health knowledge indicated greater awareness of oral health. 3. OHIP-14 was higher for those who lived with their parents than those who in did not(P=0.012). 4. There exhibits a proportional relationship between subjective awareness of oral health and OHIP-14(r=0.297). Conclusion: It was found that subjective awareness of oral health partially influences to OHIP-14. In other words, subjective awareness of oral health has an effect on the quality of life related to oral health. Hence, there needs more effort on oral health education and oral disorder prevention activities in order to improve subjective awareness of oral health.