The purpose of this study is to analysis of the difference between dementia policy perception, dementia knowledge, dementia attitude and dementia prevention behavior of middle-aged. The subjects were 217 middle-aged in their 40 to 64 years old who lived in D and G cities. The mean sore of were dementia policy perception 75.42±8.52, dementia knowledge 8.71±1.90, dementia attitude 28.55±5.10, dementia prevention behavior 27.04±3.35. Dementia knowledge were significant differences in gender, number of diseases, source of dementia information. Dementia attitudes were significant differences in gender, age, education, dementia in family, dementia living together, job status, early examination, source of dementia information. Dementia prevention behavior were significant difference in dementia living together and early examination. The most category of dementia prevention behavior was 'cigarette smoking(Inverse question)', and blood pressure and diabetes management' were the lowest. Therefore, development of a professional and systematic dementia education program to raise the awareness of dementia policy among middle-aged adults and form the right dementia knowledge and positive dementia attitude. Development of customized dementia prevention behavior programs to maintain cognitive activities, social activities, proper eating habits, and health care is needed.