Purpose:The purpose of this study is to examine adolescents' knowledge and attitudes towards dementia and to provide basic data for educating about knowledge of dementia and strengthening positive attitudes towards dementia. Methods: This study used a descriptive research design. The subjects were 502 middle and high school students. A questionnaire organized by 16 questions of knowledge and 10 questions of attitudes towards dementia was used. Results: The subjects' knowledge level of dementia was low, and average score was 8.89±2.95. The questions with low rate of correct answer were "Dementia is caused by several dozens of diseases such as internal medicine, neurology, psychiatry, etc.", "In spite of the dementia, patients can enjoy their favorite things." The subjects' average score of attitudes towards dementia was 3.72±0.58. Questions of negative attitudes were "I don`t want to be closed to patients of dementia.", "I watch information or prevention about dementia in mass communications media." The relationship between dementia-related knowledge and attitudes showed positive correlation. Conclusion: The result means the mediation is necessary for improving dementia-related knowledge and strengthening positive attitudes in adolescents. The education programs should be proceeded to provide adolescents with correct information about dementia.